US3650667A

US3650667A - Laundry process for producing fabrics that are substantially free from bacteria and bacterial spores

Info

Publication number: US3650667A
Application number: US884694A
Authority: US
Inventors: Louis F Luechauer
Original assignee: Steiner American Corp
Current assignee: Steiner American Corp
Priority date: 1969-02-26
Filing date: 1969-12-12
Publication date: 1972-03-21
Anticipated expiration: 1989-03-21
Also published as: FR2032430B1; GB1307691A; DE2008877A1; CH826271A4; SE366342B; CH523370A; BE746522A; CA924454A; NL7002670A; FR2032430A1; CH529874A

Abstract

Method (A) for laundering fabrics comprising washing said fabrics in hot water at a medium water level in the presence of soap and a sequestering agent; flushing the fabric load; washing the fabric at a low water level for about 10 to about 15 minutes at a temperature of about 175* to about 195* F. in the presence of a strong alkali and soap or a detergent; flushing the fabric load; bleaching the fabric load in hot water at a medium water level with an oxygen-containing bleach which is hydrogen peroxide or a material that forms hydrogen peroxide or nascent oxygen in the presence of water at a concentration of about 0.1 to about 0.2 percent by weight of the dry fabric weight, the bleaching being carried out at a temperature of at least about 175* F. for about 6 to about 10 minutes; rinsing the fabric load; souring the fabric load in the presence of a souring agent and a water soluble germicide at a concentration level sufficient to inhibit the growth of mildew in the laundered fabric, and extracting the water from the soured fabric load. Method (B) for laundering fabrics comprising washing said fabrics in hot water at a medium water level in the presence of soap and a sequestering agent; flushing the fabric load; treating the fabric load at a low water level at a water temperature of about 140* to about 160* F. in the presence of an oxygencontaining bleach which is hydrogen peroxide or a material which forms hydrogen peroxide or nascent oxygen in the presence of water for a time sufficient to obtain substantially uniform penetration of the oxygen-containing bleach into the fabric with the concentration of oxygen-containing bleach ranging from about 0.1 to about 0.2 percent by weight of the dry fabric; increasing the temperature of the fabric load to at least about 175* F. in the presence of a strong alkali and soap or a detergent for about 10 to about 15 minutes; rinsing the fabric load; souring the fabric load in the presence of a water-soluble germicide at a concentration level sufficient to inhibit the growth of mildew in the laundered fabric, and extracting the water from the soured fabric load. The use in either of the above described methods (A) and (B) of a hypochlorite bleach step subsequent to the treatment with the oxygen-containing bleach and prior to the souring treatment to remove stains from the fabric.

Description

United States Patent Luechauer [54] LAUNDRY PROCESS FOR PRODUCING FABRICS THAT ARE SUBSTANTIALLY FREE FROM BACTERIA AND BACTERIAL SPORES [72] Inventor: L ouis F. Luechauer, Salt Lake City, Utah [73] Assignee: Steiner American Corporation, Salt Lake City, Utah 221 Filed: Dec. 12,1969

21 Appl.No.: 884,694

Related U.S. Application Data [63] Continuation-in-part of Ser. No. 802,670, Feb. 26,

1969, abandoned.

Primary ExaminerMayer Weinblatt A!torneyPhilip Subkow, Thomas H. Jones and Kendrick and Subkow s7 1 ABSTRACT Method (A) for laundering fabrics comprising washing said fabrics in hot water at a medium water level in the presence of soap and a sequestering agent; flushing the fabric load; wash- 51 Mar. 21, 1972 ing the fabric at a low water level for about to about minutes at a temperature of about 175 to about 195 F. in the presence of a strong alkali and soap or a detergent; flushing the fabric load; bleaching the fabric load in hot water at a medium water level with an oxygen-containing bleach which is hydrogen peroxide or a material that forms hydrogen peroxide or nascent oxygen in the presence of water at a concentration Method (B) for laundering fabrics comprising washing said fabrics in hot water at a medium water level in the presence of soap and a sequestering agent; flushing the fabric load; treating the fabric load at a low water level at a water temperature of about to about F. in the presence of an oxygencontaining bleach which is hydrogen peroxide or a material which forms hydrogen peroxide or nascent oxygen in the presence of water for a time sufficient to obtain substantially uniform penetration of the oxygen-containing bleach into the fabric with the concentration of oxygen-containing bleach ranging from about 0.1 to about 0.2 percent by weight of the dry fabric; increasing the temperature of the fabric load to at least about F. in the presence of a strong alkali and soap or a detergent for about 10 to about 15 minutes; rinsing the fabric load; souring the fabric load in the presence of a watersoluble germicide at a concentration level sufficient to inhibit the growth of mildew in the laundered fabric, and extracting the water from the soured fabric load.

The use in either of the above described methods (A) and (B) ofa hypochlorite bleach step subsequent to the treatment with the oxygen-containing bleach and prior to the souring treatment to remove stains from the fabric.

28 Claims, N0 Drawings kAUbliDRY PRGCES FOR PRODUCHNG FABRICS THAT ARE fitlBSTANTlALLY FROM BACTERIA AND lBA CTERllAlL SPORES This application is a continuation-in-part of my earlier filed copending patent application Ser. No. 802,670 filed Feb. 26, 1969 and now abandoned.

A major segment of the commercial laundry industry involves suppliers who supply their own linens to users, such as doctors offices, beauty shops, industrial plants, hotels, restau rants, and the like. A linen supplier of this type furnishes a continuous source of clean linens to its customers, delivering clean linens on a regular basis, picking up soiled linens on a regular basis, and laundering the soiled linens in its own plant.

ivlany of the users of linens, as outlined above, require linens which are substantially free of bacteria or bacterial spores. This is especially true in the case of a user such as a doctors office or a hospital where the medical procedures employed require a sterile environment. Until quite recently, it was assumed by commercial launderers that the severe laundering conditions which were used produced a completely sterile laundered product. This assumption was based on bacterial samplings made from the surface of the laundered product which, in general, showed that the laundered product was free from any bacteria or bacterial spores.

Recently, it has been discovered that heat resistant bacterial spores may be embedded within the interstices ofa laundered product, such as a continuous towel, and can survive the severe laundering conditions used by a commercial laundry. This was discovered by bacterial studies in which small portions of the laundered items were mascerated and the mascerated portions were then placed in growth medium capable of sustaining bacterial growth, preferably even in the presence oforganometallic compounds such as phenyl mercuric acetate. Such tests showed that commercial linens having a hygenically clean surface, can and ofttimes do, contain a large number of heat resistant bacterial spores embedded within their interstices. Such embedded spores may, of course, pose a health hazard since the spores, given the right growth conditions, may become activated to produce bacteria. This result would be very harmful if the linens were employed in a hospital or doctors office. Also, in the case of linens used by many different people, such as continuous toweling, the release of bacteria from within the interstices of the towel could result in rapid spreading of the bacteria. If the bacteria were a disease-producing type, the net result would be a spreading ofthe bacteria in epidemic proportions.

Various means of sterilization are known, such as the use of intense heat, the use of ultraviolet light, etc. Most such methods are, however, so severe that they would damage linens and sharply increase the suppliers costs due to the need for more frequent linen replacement. Also, many methods of sterilization would discolor linens, such as table napkins or waitresses uniforms. Lastly, many methods of sterilization are not compatible with the existing laundry equipment and the procedures previously employed in commercial laundering and their adoption would require very extensive changes in present laundering procedures and equipment.

in solving the above problems, 1 have devised laundering processes which can be carried out in existing laundering equipment, which do not damage fabrics, and which are effective in killing heat-resistant bacterial spores embedded within the interstices of laundry. in conjunction with my methods, I have devised a number of laundry testers to provide effective quality control by the operator during the laundry procedures.

in discussing my invention, it is believed desirable to first define a number of terms which are used in the laundry industry and which will be referred to in describing my invention. The term light soil refers to linens which are neither badly stained or which contain appreciable quantities of loose soil. Sheets used by hotels are considered light soil and, in many cases, towels from barber shops fall into the same category. The weight of the soiling material in items of this type is negligible and typical soiling may be taken as approximately one-half pound ofdry soil (0.2 percent) for a 300-pound load,

The term medium soil" refers to items such as waitress dresses, towels for beauty shops, and, in some cases, napkins from restaurants. The weight of the soiling material in items of this type is greater than in items in the light soil category, above, and items in this category will also contain more stains than items in the light soil category. By way of example, medium soil items in the light soil category. By way of example, medium soil items may typically contain approximately five pounds of dry soil (2.0 percent) per 300-pound load.

items which fall into the category of heavy soil" not only contain stains but also contain appreciable amounts of loose soil which must be flushed or rinsed out of the washing machine in order to avoid gray work. Items in this category inelude, for example, aprons from butcher shops, towels from restaurants, and swipes that are used for clean-up purposes. Typically, the weight of the soiling material for items in this category will be approximately 30 pounds of dry soil (10.0 percent) for a BOO-pound load.

items which fall in the category ofindustrial soil contain oily soil rather than fatty soil and include, for example, linens such as towels and coveralls from garages and industrial plants. The weight of the soiling material in this category is far greater than in any other-for example, approximately pounds of dry soil (30.0 percent) for a 300-pound load may be taken as typical.

in accord with my invention, I have devised methods for laundering fabrics to produce a clean fabric and one which is substantially free from bacteria and bacterial spores. One such method (A) is described in my previous copending U.S. application Ser. No. 802,670, which is now abandoned. Also disclosed in my previous copending U.S. application are detectors which may be utilized in monitoring the effectiveness of the treatment of my laundry processes in terms of killing bacterial spores, while at the same time, not injuring the laundered fabric. The subject matter of my prior copending application is carried forward into the present application and is incorporated herein by reference.

Subsequent to the filing of my prior application, U.S. Ser. No. 802,670, which is now abandoned I discovered an improved process (B) which improvement increases the effectiveness of my process (A) in killing heat resistant bacterial spores. Certain types of linens, such as linens used in a slaughter house, may have heat resistant bacterial spores embedded in the interstices thereof which are more difficult to kill than heat resistant bacterial spores found in other types of commercial linens. lviy improved process (B) is especially suitable for laundering linens of this type while my previously disclosed process (A) is satisfactory in killing heat resistant bacterial spores in most other types of linens.

in previous laundry procedures, the first laundering step involved thoroughly wetting the load with water. in the event that the load was bloody, the temperature of the water was about F. and if the load was not bloody, the temperature of the water was about F. 1n laundering fabrics according to my method (A), I have found that it is undesirable to begin the laundry cycle with a water-wetting of the load as previously employed since this has been found to redistribute bacteria and bacterial spores contained within the fabric. In accord with my method (A), the first step in the laundry operation is a mild washing step. Hot water, i.e., about 160 F., is added to the load, together with soap at a concentration of about 0.02 percent by weight of the dry fabric and sequestering agent is present at a concentration in the order of about 0.01 percent to about 0.05 percent by dry weight of the fabric. Various sequestering agents are known and include, for example, polyphosphates and Versene, which is the sodium salt of ethylene diamine tetraacetic acid.

The use of a sequestering agent in the first step of the laundry operation is essential to my overall process and, to my knowledge, is a departure from laundry procedures previously employed. Alkali is not added to the initial wash cycle since the presence of alkali sets bloody stains and, moreover, the presence of alkali in the initial wash tends to salt out the soap or other detergent which is employed with the result that the wash bath loses its dirt-suspending power. The water level employed during the first step is a medium level, i.e., about 6 to 8 inches, and the time of the first step is about 3 to minutes with agitation, using, for example, a 42-inch X 84-inch or a 42- inch X 96-inch open pocket washer. Open pocket washers, as employed, contain one vertical partition mounted perpendicular to the axis of the washer and dividing it in two. The washer contains no horizontal or radial partitions and rotates at a constant speed of about 21 revolutions per minute. The degree of agitation obtained is determinated by the water level. As the water level is increased, the degree of agitation is decreased and as the water level is decreased, the agitation is increased.

My laundering procedure (Method A) is particularly suited for the washing of continuous towels. A continuous towel will, for example, have a length of about 50 yards and it is tied into a bundle for washing. The towel bundles are formed by folding the towel into 36-inch lengths to form a bundle having a length of about 36 inches and a height of about 6 inches. The bundle is then tied in two places and is washed in this manner. In the case of a bundled fabric, such as continuous toweling, it is difficult to penetrate the interstices of the toweling at the center of the bundle during washing to kill any bacteria or bacterial spores contained therein. it is particularly important not to redistribute the bacteria or bacterial spores in washing a continuous towel as resulted in the initial water-wetting step employed in previous laundering procedures. The initial waterwetting step previously employed also had the disadvantage of embedding bacterial spores within the interstices of the fabric being washed. This resulted from the force of the water striking against the fabric during agitation. In contrast, in the first step of the present process, the dirt and bacteria are loosened and placed in suspension within the wash water such that they are removed from the fabrics and are not embedded therein.

As stated previously, the quantity of soap, e.g., sodium stearate or detergents, including anionic and nonionic detergents, which is present during the first step is at a concentration of about 0.02 percent by dry weight of the fabric being laundered. The amount of soap employed can, of course, be varied depending upon the salt content of the water. If the water is deionized, the soap content can be reduced proportionately.

Following the first washing step, the load is drained and is then flushed one or more times by introducing hot water, e.g., about 160 F., into the machine to a high level, i.e., a water level of about 12 inches. During flushing, the load is subjected to mild agitation for about 3 minutes. As stated previously, the speed of rotation of the washer is maintained constant and the degree of agitation determined by the water level. After mild agitation for about three minutes, the load is drained and, if desired, can be subjected to a second flush cycle in the same manner as described.

Following flushing, the laundry is then subjected to a washing cycle for a period of about to about 15 minutes. The wash water is maintained at a temperature of about 175 to about 195 F. at a low water level, such as about three inches. The use of a low water level achieves a high degree of mechanical agitation. A strong alkali, such as caustic soda, is present at a concentration from about 0.2 to about 0.5 percent by weight of the dry weight of the fabric and soap or detergent is present at a concentration of about 0.1 to about 0.3 percent by weight of the dry weight of the fabric. If desired, a portion, such as about percent of the soap or detergent may be replaced with a sequestering agent, as defined previously.

The use of a strong alkali, as a general matter during the washing step of longest duration in the laundering operation, is a procedure which differs from laundering procedures now employed. Previously, very few plants used caustic soda as an alkali unless it was buffered with soda ash, phosphate, etc. However, 1 have found that in my overall laundering procedure it is necessary to use a strong alkali, such as caustic soda, in the primary washing step in order to provide a procedure which produces hygenically clean linens.

1f the linens being laundered are colored, a small quantity of dye, such as about one-quarter to about one-half ounce per one hundred pounds dry weight of fabric, is added for restorative purposes. The various dyes which may be employed are well known to the industry; For example, in washing blue fabrics, the dye known as Direct Copper Blue manufactured by Ciba Company, may be used, and in the case of red toweling, Congo Red may be used. With yellow towels, a yellow dye such as Ciba RLSW may be used, and for green toweling, the dye sold as Ciba Direct Green CBM may be used. The quantity of dye, as set forth above, is used for restorative purposes to maintain the color of the fabric.

Following the washing step, the load is subjected to several flushing steps. Generally, the load is flushed twice; however, if a great deal of dirt is present, the load may be flushed three times. During a flushing operation, hot water at a temperature of about 160 F. is added to the machine to a water level of about 12 inches and the load is subjected to mild agitation for a period of about 3 minutes and thereafter drained. The load may be subjected to additional flushing treatments in the same manner, as desired.

Following the flushing to remove dirt and bacteria, the load is then bleached with an oxygen containing bleach which is hydrogen peroxide or a material which forms hydrogen peroxide or nascent oxygen in the presence of water. The bleach is present at a concentration level ranging from about 0.1 to about 0.2 percent by weight of the dry fabric weight. The term oxygen-containing bleach includes liquid hydrogen peroxide, solid sodium peroxide, or equivalent water soluble noncolor forming salts, such as sodium perborate. A peroxide is added in the form of an aqueous solution such as, for example, a 35 percent aqueous solution of hydrogen peroxide. In admixture with the peroxide is hot water, e.g., about 160 F., at a medium level of about 6 to 8 inches. Soap, such as sodium stearate, or other anionic or nonionic detergent, is present at a level ranging from about 0.01 to about 0.02 percent by weight of the dry fabric load. As discussed previously, the quantity of soap employed can be reduced considerably if the water is softened and preferably deionized. No strong alkali, e.g., caustic soda, or sequestering agent is added to the bleach cycle.

After addition of the hot water and other ingredients to the washing machine, the load is heated, in the event that the water is not already at this temperature, to a temperature of at least about 175 F. The load is then maintained at this temperature for about 6 to about 10 minutes with agitation.

Although peroxides are not generally employed in commercial laundering operations for bleaching, the concept of using a peroxide for this purpose if not novel, per se. To my knowledge, however, the use of peroxide in conjunction with the other steps of my laundering procedure (Method A) so as to provide both clean and hygenically sterile fabrics, is new. I have found that the use of an oxygen containing bleach in conjunction with the other steps of my laundering process provides not only effective bleaching but an effective kill of heatresistant bacterial spores which may be embedded within the interstices of the fabric being laundered.

Following the bleaching treatment, the load is subjected to a number of rinses. Although the number of rinse cycles is not critical to my process, 1 generally find it advantageous to use three rinse cycles following the bleaching treatment. In each cycle, water is introduced into the machine in an amount sufficient to provide a high water level, e.g., about 12 inches, and thereafter the load is subjected to mild agitation at the high water level for a period of about 3 minutes and then drained. 1n the course of the rinse cycles, the temperature of the load is gradually reduced to about F. Assuming, for example, that the temperature of the load following the bleach treatment was 175 F., the water for the first rinse cycle could be at a temperature of about 150 F., the water employed for the second rinse cycle could be at a temperature of about F., the water employed for the third rinse cycle could be at a temperature of about 105 F. These particular temperatures are arbitrarily selected merely to demonstrate the gradual reduction in temperature with each rinse cycle.

Following the rinse cycles, the load is then subjected to a souring treatment. The souring treatment is used to provide the fabric with a pH of about 5.4, which is that of the human skin. If desired, a souring step can be used to provide a higher pH of the fabric such as about 6.0. A typical souring agent is ammonium silicofluoride. The concentration of souring agent may range from about 0.02 percent to about 0.05 percent by weight of the dry fabric load and can be varied depending upon the pH of the city water which is used. In addition, there is added a water-soluble germicide at a concentration level sufficient to inhibit the growth of mildew in the laundered fabric. The concentration of germicide can, of course, be varied, depending upon its potency. Typically, the concentration 'level of germicide may range from about 0.004 to about 0.008 percent by weight of the dry fabric load. Typical germicides include water soluble organometallics, such as phenyl mercuric acetate, which is a standard germicide.

During the souring treatment, the load is subjected to agitation at a medium water level (about 6 to 8 inches) for a period of about 5 minutes. Following the souring treatment, the water is then extracted from the load, either centrifugally or by pressure, and the fabric may then be ironed.

As described above, my novel laundry process (Method A) provides fabrics which are not only clean, i.e., free from dirt, but also essentially free from bacteria and bacterial spores before exposure to air. Although many methods are known for laundering fabrics and many methods are known for sterilization, to my knowledge there is no satisfactory process available which can provide fabrics which are both clean and essentially free from bacteria and bacterial spores without excessive fabric damage. As described, my laundry process may be used for cleaning linens containing light soil, medium soil, heavy soil, or industrial soil. It should be understood, of course, that the detergency level and the number of rinse cycles may be increased or decreased depending upon the soil level in the fabric.

As described up to this point, Method A, as previously disclosed in copending application Ser. No. 802,670, which is now abandoned comprises eight steps which are as follows:

1. Washing the fabric load in hot water at a medium water level in the presence of soap or a detergent and a sequestering agent;

2. Flushing the fabric load one or more times;

3. Washing the fabric load at a low water level for about 10-15 minutes at a temperature ofabout 175 to 195 F. in the presence ofa strong alkali and soap or a detergent;

4. Flushing the fabric load;

5. Bleaching the fabric load in hot water at a medium water level with an oxygen-containing bleach which is hydrogen peroxide or a material which forms a hydrogen peroxide or nascent oxygen in the presence of water, the oxygen-containing bleach being present at a concentration of about 0.1 to about 0.2 percent by weight of the dry fabric weight, and the bleaching being carried out at a temperature of at least about 175 F. for about 6 to about 10 minutes;

6. Rinsing the fabric load;

7. Souring the fabric load in the presence ofa water-soluble germicide at a concentration level sufficient to inhibit the growth ofmildew in the laundered fabric, and

8. Extracting the water from the soured fabric load.

In my improved Method (B) which is particularly suitable for killing heat resistant spores as found in fabrics from slaughter houses, a slightly different procedure is used than in Method (A). To illustrate the difference between my Method (B) and my Method (A), the following steps are employed in Method (B):

I 1. Washing the fabric load in hot water at a medium water level in the presence of soap or a detergent and a sequestering agent;

2. Flushing the fabric load one or more times;

3. Treating the fabric load at a low water level at a water temperature of about 140 to about 160 F. in the presence of an oxygen-containing bleach, which is hydrogen peroxide or a material which forms hydrogen peroxide or nascent oxygen in the presence of water, for a time sufficient to obtain substantially uniform penetration of the oxygen-containing bleach into the fabric, the concentration of oxygen-containing bleach ranging from about 0.1 to about 0.2 percent by weight of the dry fabric weight;

4. Increasing the temperature of the fabric load to about to about F. in the presence of a strong alkali and soap or a detergent while maintaining the increased temperature for about 10 to about 15 minutes;

5. Flushing the fabric load one or more times;

6. Souring the fabric load in the presence of a water-soluble germicide at a concentration level sufficient to inhibit the growth of mildew in the laundered fabric, and

7. Extracting the water from the soured fabric load.

Comparing the steps employed in Method (B) with those employed in Method (A), it will be observed that the principal difference resides in the manner in which the oxygen-containing bleach is employed. In Method (A), the fabric load is first washed in the presence of a strong alkali in step (3) and thereafter in step (5) the fabric load is treated with an oxygencontaining bleach at a temperature of at least about 175 F. In Method (B), the oxygen-containing bleach is brought into contact with the fabric load in step (3) to obtain substantially uniform penetration of the oxygen-containing bleach into the fabric load. It is only then in step (4) that a strong alkali is added and the temperature of the fabric load is increased to a temperature of about 175 to about 195 F. It has been found that the efficiency of the oxygen-containing bleach in killing heat-resistant bacterial spores embedded within the interstices of fabric is increased by first obtaining substantially uniform penetration of the bleach into the fabric load and then activating the bleach by the addition of strong alkali coupled with raising the temperature to about 175 to about 195 F.

The steps required for Method (B) are more complex in that they require the addition of two different laundry supplies to the same wash load, i.e., first the addition of the oxygencontaining bleach material in step (3) and later the addition of a strong alkali in step (4). The steps of Method (A) do not require the addition of two laundry supplies to the same wash load and thus this method provides an easier procedure for use in a commercial laundry. For this reason, Method (A) is preferred for laundering fabrics which do not require the conditions of Method (B) to kill heat-resistant bacterial spores embedded within the fabric.

1n practicing my Method (B), l have found that agitation of the fabric load at a low water level, i.e., about 3 to 5 inches of water, for a period of about 3 to 5 minutes is generally sufficient to obtain substantially uniform penetration of the oxygen-containing bleach material into the fabric load. The speed of rotation of the washer, as defined previously, is relatively constant at about 21 revolutions per minute. If desired, of course, the speed of rotation of the washer may be varied, as, for example, from about 18 to about 26 revolutions per minute. The precise conditions employed in steps 3 and 4 of my improved process may, of course, be varied in accord with the type and size of the laundry equipment and the quantity of fabric overload.

Steps 1, 2, 5,6 and 7 of Method (B) are the same as steps 1, 2, 6, 7 and 8, respectively, of Method (A), as described in detail previously. In describing both Method (A) and Method (B), the term dry fabric weight is used. This term refers to the weight of the soiled fabrics in an as is condition when received by the laundry. Thus, the term includes the weight of soil in the fabric, the weight of the fabric itself and the weight of any moisture in the fabric due to atmospheric humidity, i.e., from a few percent ranging up to as high as possibly 10 percent on a very humid day. The terms flushing" and rinsing, as used in defining my Methods (A) and (B), are in terchangeable since the conditions used for flushing" are essentially the same as those used for rinsing. The only difto remove a particular laundry supply from the load, e.g., in

removing alkali to reduce the pH of the load.

In step (4) of Method (B), alkali is added in an amount sufficient to give a pH of about 1 1.7 to about 12.1 in the presence of sodium perborate or about 12.1 to about 13 in the presence of a peroxide. Similarly in step (3) of Method (A), the strong alkali is present in an amount sufficient to give a pH of about 11.7 to about 12.1 in the presence of sodium perborate or about 12.1 to about 13 in the presence of a peroxide. Thus, step (4) of Method (B) is quite similar to step (3) of Method (A). If a dye is added for color restorative purposes in Method (B), it may be and preferably is added in step (3) before addition of the strong alkali in step (4). Also, however, it can be added with or after addition of the strong alkali in step (4).

An optional step which may be incorporated into either my Method (A) or Method (B) involves the use ofa hypochlorite bleach. This step may be employed in order to facilitate stain removal. Inasmuch as the oxygen-containing bleach material will neutralize the hypochlorite bleach, it is necessary that the fabric load be flushed or rinsed a sufficient number of times after treatment with the oxygen-containing bleach material so as to reduce the content of the oxygen-containing bleach material to a level where it does not interfere unduly with the hypochlorite bleach. As a practical matter, I have found that about three flush or rinse steps is satisfactory to reduce the content of oxygen-containing bleach material to a level where it does not interfere with the hypochlorite bleach.

Dealing specifically with my Method (A), the use of a hypochlorite bleach step may be termed step (6a) and would follow step (6) in which the fabric load is rinsed to reduce the content of oxygen-containing bleach material to a satisfactory level. In carrying out the hypochlorite bleach step, the hypochlorite is present in an amount sufficient to remove stains and may vary in concentration, for example, from about 50 to about 1,000 parts per million, depending upon the soil level or stains which are to be removed. During the hypochlorite bleach step, a medium water level is employed in the washer with a water temperature of about 145 F. The fabric load is agitated during the hypochlorite bleach step for a time ranging from about 5 to about 7 minutes.

As the hypochlorite bleach material, there may be employed a water-soluble hypochlorite salt or a material which yields a water-soluble hypochlorite on dissociation in situ. Typical of suitable materials are sodium hypochlorite, lithium hypochlorite, dichlorodimethyl hydantoin, and chlorinated metallic salts of isocyanuric acid, e.g., the sodium or potassium salts. If desired, soap may also be present during'the hypochlorite bleach step. Following the bleach step [step6a], in Method (A), the fabric load may be rinsed several times before the souring step (7). The rinsing may be termed step (6b), as applied to my Method (A). The duration of a single rinse cycle is approximately 3 minutes. During the course of the rinse cycle the temperature of the fabric load may be gradually reduced to about 1 10 Fv before being subjected to the souring treatment (step7).

As applied to my Method (B), as described above, a hypochlorite bleach step would be step (5a) and the rinsing would be step (5b). These steps (5a) and (5b) would be carried out in the same manner as described for steps (6a) and (6b) ofMethod (A).

In laundering fabrics in accord with my novel processes, i.e., Methods (A) and (B), it is convenient to use laundry testers for insuring quality control. The use of laundry testers is described in my previous patent, U. S. Pat. No. 3,094,373 issued June 18, 1963, the disclosure of which is incorporated herein by reference. As described in my patent, a laundry tester found suitable for laundering processes of the prior art employed a-largeswatch of poplin having its edges pinked and having 8 individual detectors mounted thereon. In the laundry tester of my 'p'atent,the individual detectors, Nos. 1, 2 and 3, were used to sense the bleaching intensity level used in the laundry process while employing a hypochlorite bleach which was usually added in the form of sodium hypochlorite. Detectors Nos. 4, 5, 6, 7 and 8, as described in my prior patent,'were employed to monitor the temperature and time, alkali level, and the degree of agitation or mechanical action used in the overall laundry cycle.

Detectors Nos. 4-8, as described in my patent, may be employed in my present processes for monitoring the time, temperature, degree of alkalinity, and mechanical action used by the laundry operator. Since my present processes require the use of an oxygen-containing bleach which is hydrogen peroxide or a material which forms hydrogen peroxide or nascent oxygen on contact with water in the bleaching step, detectors 1, 2 and 3 of my patent are not required for the present processes. If, however, an optional hypochlorite bleach step is employed in either of my processes, detectors 1, 2 and 3 of my patent are employed to monitor the efficiency of the hypochlorite bleaching step.

I employ a series of detectors, each of which has a different sensitivity to peroxide and undergoes a color change at a particular peroxide level. At the present time I employ five such detectors, and each detector meets the following specifications:

1. It is unaffected by the laundry procedure which precedes the bleaching step;

2. It produces a color change that is permanent and persists for one or two months after the use of the detector;

3. It changes color on treatment with peroxide while, at the same time, it is sufficiently shielded to avoid a loss of the detector pigment by the combined effect of heat, alkali, soap or detergent and mechanical action which are encountered in the laundry procedure prior to the bleaching step;

4. It does not undergo a color change during the souring step, and

5. It exhibits a color change that is pronounced enough to be recognizable without the use of special lighting conditions.

Each of the five detectors which 1 now employ to detect varying levels of peroxide employs a paper that is impregnated with chromic chloride and may include also small quantities of titanium oxide as a brightener. The chromic chloride and titanium oxide may be held to the surface of the paper by a conventional resinous binder. By way of illustration, the binder may comprise a carrier resin dissolved in a fast evaporating solvent. Among the resins which may be used are ethyl cellulose, either alone or in admixture with polyethylene, modified alkyd resins or zein. Various solvents which may be used with ethyl cellulose as the resin include methylene dichloride, benzene, toluene, ethyl alcohol, methyl alcohol, aromatic hydrocarbons and chlorinated hydrocarbons.

Also, for example, a mixture of chromic chloride and titanium oxide may be mixed with a boiled, i.e., oxidized, linseed oil mixed with a petroleum thinner. The paper may be immersed in the linseed oil mixture and then air dried at an elevated temperature to remove the thinner. The chromium chloride, in its anhydrous form is purple in color and, on exposure to steam or moisture, it picks up six molecules of water but is still putple in color.

The impregnated paper can be prepared so that it will have a greenish-gray color which matches plate 27D-l in Maerz and Paul Dictionary of Color, published by McGraw-Hill Book Company, Inc. in 1950. This is a standard reference work on color. The best method for preparing a suitable indicator paper for use in my detectors is to allow the purple colored (Plate 4lF-5, Maerz and Paul) paper defined above to age at room temperature and atmospheric moisture. On aging the paper becomes greenish-gray (Plate 27D-l, Maerz and Paul). During aging, the pH of the pigment changes to become more alkaline. The pH produced by adding 25 grams of the shredded purple paper to ml. of distilled water is in the range of 5.0 to 6.0. After aging to a greenish gray color, the pH resulting from adding 25 grams of the shredded paper to 100 ml. of distilled water is 8.0 to 9.0. The weight ratio of chromic chloride to titanium dioxide in the pigment may be about 9 to l.

As described above, the impregnated paper is allowedto age at room temperature for six months or more and undergoes a color change from purple to gray and finally to greenish gray. It is the aged paper having a greenish-gray coloration which I employ in my detectors for sensing peroxide efficiency in my processes.

In providing a series of peroxide detectors, the most sensitive detector (A) contains an aged impregnated paper having a ratio of about I to 9 of titanium oxide to chromium chloride. The pigment also contains sodium carbonate in an amount sufficient to raise the pH produced by adding the paper to water in the manner defined above to a level of about 9.5. The paper is then stapled to a single strand of l6-ply cotton twine which is held against the back of the paper by -mil nylon film. The three items are then enclosed in a packet formed of a single layer of 2-mil Nylon Autoclavable film with the cotton twine extending through a side of the heat-sealed portion of the packet.

The Nylon Autoclavable film is a Rilsan Nylon 1 l film, which is a vegetable derivative of l l-amino undecanoic acid polymer (Nylon 11) made from castor oil and used in pure form without the addition of plasticizers or fillers. The film may be purchased from Vail Medical Products, 923 Cole Avenue, Los Angeles, Calif. 90038.

The next most sensitive detector comprises a paper impregnated with anhydrous chromium chloride and titanium oxide, as described previously, which is then aged in a normal manner to a greenish-gray coloration. The aged detector is then sealed in a packet formed ofa single layer of 2-mil Nylon Autoclavable film. The 2-mil film, after scaling, is then punctured with a /zto 2-millimeter needle (preferably about I millimeter) which enters the film adjacent the back of the indicator and passes through the paper and the film on the other side ofthe paper. This detector is denoted (B).

The next most sensitive detector (C) employs the same indicator paper as used in detector (B). The paper is stapled to four strands of rayon cord which strands should be adjacent to each other. The detector paper is then encased in 2-mil Nylon Autoclavable film, as described previously, and the rayon cords extend through the heat-sealed portion of the packet. These strands act as wicking which can carry liquid to the inside ofthe film packet.

The next most sensitive detector is denoted (D) and is the same as detector (C), except that only two strands of rayon cord are employed which extend through the heat sealed portion ofthe two mil film packet.

The least sensitive detector (E) employs the same aged indicator paper as described above. with respect to detectors (B) through (D) and the detector is completely encased in a heat sealed packet of lmil Nylon Autoclavable film which is identical chemically to the 2-mil film.

The effect of peroxide on the indicator used in the detectors is to cause a color change in the paper from greyish-green to brownish tan [Maerz and Paul Plate 131-7]. If the paper changes to a pale reddish tan color [Maerz and Paul Plate 11 7], this is an indication that the peroxide concentration employed is far in excess of that required to kill bacterial spores and will be harmful to the fabric.

Employing the five detectors (A) through (E) above, a color change is denoted in detector (A) from greyish-green to brownish tan every time an item is laundered in accord with my process, even at the lowest permissible peroxide concentration. In the case of detector (B), a brownish tan coloration near the punctured portion indicates that the peroxide level is sufficient to produce a bacterial kill that is more rapid than that provided by a color change in detector (A). When the peroxide level employed is sufficient to cause a color change in detector (C) to brownish tan, the entire inked area in detector (B) changes to a brownish tan coloration.

A color change in detector (C) to brownish tan is definite evidence that the peroxide bleaching intensity is sufficiently high to not only kill bacteria and bacterial spores but to main tain a low count for an indefinite period of time. The color change here to brownish tan is gradual.

A color change in detector (D) to brownish tan indicates a rapid kill of existing bacteria and bacterial spores. Fabric will be damaged more severely if there is a color change in detector (D) than would be the case when only detectors (A), (B) and (C) undergo a change in color.

A color change in detector (E) to brownish tan indicates a very high peroxide level which produces a very high bacterial killing intensity. A color change in detector (E) to brownish tan would only be desirable in, for example, a first laundering of fabrics according to my process, the fabrics having a very high level of embedded bacteria and bacterial spores. This high peroxide level would be sufficient to kill all the embedded bacteria in one washing. However, the damage which would result to fabrics from using this peroxide intensity would be so excessive that a laundry facility could not afford to use this peroxide level on a day-to-day basis.

To demonstrate the color changes occurring in the indicator paper, there is presented the following table:

Maerz and Paul Colors Plate 4lF-5 Plate 27D-l Plate ZSA-l Plate 131-3 Lll Plate l3J-7 Plate I I7 As described above, I have provided novel laundry procedures which both clean and produce fabrics that are essentially free from bacteria and bacterial spores without excessive harm to the fabric itself. In addition, I have provided a series of novel detectors for sensing the peroxide intensity employed in terms of its effect on killing bacteria and bacterial spores and its damage to the fabric being laundered. By employing a number of such detectors, having various sensitivities to peroxide, 1 have provided a peroxide detection means which can sense a wide variety of peroxide intensities. In this manner, the laundry procedures can be effectively monitored so as to insure that the peroxide level employed is adequate to kill embedded bacteria and bacterial spores while, at the same time, not causing undue or excessive damage to fabrics.

The term substantially free from bacteria or bacterial spores as used herein refers to those counts which are analogous to standards for swimming pool water in some areas, i.e., an M.P.N. coliform count not to exceed 2.2 in ml. and, where applicable, total counts not to exceed 200 colonies per ml. At present, there is neither a uniform standard for total counts nor agreement as to whether certain bacteria may be present at any level. However, the processes of my invention do produce laundered fabrics having very low counts, e.g., less than 6,000 per 0.1 gram of mascerated fabric and complete exclusion of certain organisms commonly accepted as pathogenic to man. By way of example, the following kills of bacteria and bacterial spores were obtained, as set forth in the following Table I.

TABLE r Microbial destruction typically obtained by various commercial laundry washing processes on continuous white towels Conventional 1 Method (A) 1 Method (B) 1 Towel description Total count Spore count Total count Spore count Total count Spore count Slaughter house:

Soiled 1 All counts presented per square inch or approximately 0.1 gm. of continuous towel.

As shown in the above Table, continuous white toweling, as bleach step represents a trade-off between the desirability of described previously, was laundered by three different methods. The origin of the toweling is denoted a Slaughter House" or Normal," the term normal" referring to toweling which was not soiled by use in a slaughter house. The Conventional Process" columns indicate a typical kill of bacteria and bacterial spores in laundering a particular slaughter house towel by using a conventional heavy soil formula of the general type shown in Table VII of my U. S. Pat. 3,094,373.

The kills of bacteria and bacterial spores for particular toweling laundered by Method (A) are shown in the Table. In these runs the optional hypochlorite bleach step was not employed. Lastly, the kills obtained using Method (B) using the optional hypochlorite bleach step with lithium hypochlorite are shown in the Table. The total counts shown for both the soiled and washed towels include the total bacterial count and the total spore count. By subtracting the total spore count from the total count, one obtains the total bacterial count. All of the counts reported in the table were obtained by mascerating one square inch of the toweling, which is equal to approximately 0.] grams of toweling.

The Nylon Autoclavable film, as described previously, transmits small molecules such as water or peroxide and is substantially impervious to larger molecules such as soap, detergent or brightener. The thickness of the film is related to the permeability of the film, the 2-mil film being less permeable than the one mil film. In laundry testers which employ a means to conduct moisture to the interior ofthe packet, as, for example, the wicking or small hole described with regard to detectors A, B, C and D previously, it is not necessary for the material forming the packet to be capable of transmitting moisture. In this instance, the wicking, or hole, etc., transmits the moisture.

The function of the packet is to protect the pigment on the indicator paper and to prevent its removal by the washing steps preceding the bleaching step. In the instance where the packet is formed from one mil Nylon Autoclavable film, as defined above, or an equivalent material, the film can serve a dual function in protecting against removal of the pigment from the indicator paper while, at the same time, transmitting moisture and the peroxide to the indicator paper.

In using my detectors in the laundering of items, such as continuous toweling, which are folded and tied prior to being placed in the washer, it is frequently desirable to place the detectors at various positions within a towel bundle. Thus, for example, detectors may be placed in the outer third of the bundle, in the middle third of the bundle, and in the inner third of the bundle. By placement of the detectors in this manner, the efficiency of my processes in terms of killing bacteria and bacterial spores can be determined for the entire towel bundle.

The use of an optional hypochlorite bleach step, as defined previously, in either of my methods (A) or (B), may result in some damage to the fabrics being laundered. Thus, the decision as to whether or not to employ the optional hypochlorite stain removal on the one hand and the permissible fabric damage on the other. To assist the operator in making this decision, I have used a tensile test fabric which monitors the effect of the hypochlorite bleach step in terms of fabric damage. The tensile test fabric is supplied in rolls which are approximately 18 inches wide. The roll is cut at 10 inch intervals to provide a number of test pieces which measure ten inches by approximately 18 inches. The individual test pieces are then numbered in consecutive order as they appear on the test roll. For example, the first piece cut from the roll would be numbered 1, the next piece would be numbered 2, etc. The test pieces are used in groups of 4, for example, test pieces I, 2, 3 and 4 in one group, 5, 6, 7 and 8 in another group, etc. In dealing with the first group, pieces 1 and 4 are control pieces while pieces 2 and 3 are wash pieces. Each of the pieces, 1 through 4, is then cut into 10 strips with the direction of cutting being parallel to the direction of the warp yarns in the tensile test material. The smaller strips, 1 through 10, of the first test piece 1, are each tested on a tensile test machine and the average of the tests is determined to be the tensile strength for piece 1. The 10 individual strips in piece 4 are also tested in the tensile test machine to determine the average tensile strength for piece 4. The average of pieces I and 4 is then assumed to be the average tensile strength for the two intermediate pieces 2 and 3.

Pieces 2 and 3 are also cut into 10 equal strips along the direction of the warp of the yarns and these individual strips are used to determine fabric damage in the wash cycle. Certain of the strips go through the entire washing cycle. After going through the entire washing cycle, they are dried and subjected to tensile testing to determine the extent to which their tensile strength has been reduced from that of the control. Other of the tensile test strips are placed into the washing machine immediately prior to the hypochlorite bleach step. These strips are also subjected to tensile testing to determine the extent to which their tensile strength has been reduced by the hypochlorite bleach step. By comparing the reduction in tensile strength caused by the hypochlorite bleach step with the reduction of tensile strength caused by the overall process, the precise effect of the hypochlorite bleach step can be determined in terms of fabric damage.

In order to determine whether the treatment of the fabric load is uniform, the procedure generally is to take all ten of the individual strips from an individual test piece, for example, piece 2, and to place all of the strips in the washing machine. As in the case of my detectors, the strips may be placed at various positions within the fabric load. To illustrate, if the fabric load is composed of bundles of continuous toweling, some of the strips would be placed in the outer third of a bundle, some in the middle third, and some in the inner third of the bundle. By running the strips through the entire laundry cycle, it can be determined whether the treatment of the fabric load is uniform. For example, if certain of the strips are L3 only slightly reduced in tensile strength and other are reduced greatly in tensile strength, this is an indication of nonuniform treatment of the fabric load.

Assuming, for example, that all ofthe l strips from piece 2 were placed in the washer and had gone through the entire laundry process, all of the strips cut from piece 3 may be placed in various positions within a clean towel bundle or other piece of laundry which is added to the washer immediately prior to the hypochlorite bleach step. By comparing the tensile strengths of the strips in piece 3 after the hypochlorite bleach step, it can be determined whether the hypochlorite bleach step provided uniform treatment of the fabric load. Also, these strips determine the effect of the hypochlorite bleach step in terms of fabric damage.

If a slub or other imperfection is found in a particular piece cut from the tensile test cloth, that entire piece is discarded. If that particular piece is a control piece, e.g., either piece l or 4 of the first four pieces, the entire group of four pieces is discarded. 1f the imperfection is found in one of the intermediate wash pieces, pieces 2 or 3 of the first 4 pieces, only that particular piece is discarded. The other intermediate piece, 2 and 3, which contains no imperfections is used in the wash cycle and its tensile strength is taken as the average of the two control pieces 1 and 4.

The tensile test cloth which 1 use is made from bleached 38/2 sewing thread yarn, of extra long staple cotton made by Coats & Clark, lnc. This thread is then sent to Prodesco, Inc. for weaving into a plain weave cloth having 54 ends per inch and 49 picks per inch. One-inch wide strips running along the direction of the warp yarns are delineated on the cloth by black dyed yarn so that the one-inch wide strips cut from the individual test pieces can be ravel stripped. l found this particular material to be very useful in determining fabric damage since the material is extremely uniform in its tensile strength.

By using the tensile test cloth in the manner described above, the laundry operator can determine whether additional stain removal by use of an optional hypochlorite bleach step is justified in terms of the fabric damage which may also result. If the fabric damage is too severe, the laundry operator may well decide not to use the optional hypochlorite bleach step. On the other hand, if the fabric damage is minimal, the laundry operator may decide to use the bleach step in order to facilitate stain removal.

lclaim:

1. A method for laundering fabrics to produce fabrics which are clean and substantially free from bacteria and bacterial spores comprising:

1. Washing said fabrics in hot water at a medium water level in the presence of a soap or a detergent and a sequestering agent;

2. flushing the fabric load one or more times;

. washing the fabric at a low water level for about 10 to about minutes at a temperature of about 175 to about 195 F. in the presence ofa strong alkali and soap or a detergent;

4. flushing the fabric load;

. bleaching the fabric load in hot water at a medium water level with an oxygen-containing bleach which is hydrogen peroxide or a material which forms hydrogen peroxide or nascent oxygen in situ, said oxygen containing bleach being present at a concentration of about 0.1 to about 0.2 percent by weight of the dried fabric weight and the bleaching being carried out at a temperature of at least about 175 F. for about 6 to about 10 minutes;

. rinsing the fabric load;

. souring the fabric load in the presence ofa souring agent and in the presence ofa water-soluble germicide at a concentration level sufficient to inhibit the growth of mildew in the laundered fabric, and

8. extracting the water from the soured fabric.

2. The method of claim 1 wherein the sequestering agent is present during step l of the process at a concentration in the order of about 0.01 percent to about 0.05 percent by weight of the dry weight of the fabric load.

9. The method of claim 1 including the use ofa hypochlorite bleach step (60), wherein the fabric load is agitated at a medium water level at a water temperature of about F. for about 5 to about 7 minutes in the presence ofa hypochlorite bleach in an amount effective to remove stains from the fabric load, said fabric load then being rinsed in a step (6b) before the souring step (7).

10. The method of claim 1 wherein the oxygen-containing bleach is a peroxide.

11. The method of claim 1 wherein the oxygen-containing bleach is sodium perborate.

12. A method for laundering fabrics to produce fabrics which are clean and substantially free from bacteria and bacterial spores comprising:

1. washing said fabrics in hot water having a temperature of about F., said water containing soap and a sequestering agent, said sequestering agent being present at a concentration in the order of about 0.01 to about 0.05 percent by dry weight of the fabric load, and said washing step being carried out at a medium water level for a period in the order of about 3 to 5 minutes with mild agitation;

2. flushing the load one or more times by introducing hot water at a temperature of about 160 F. at a high water level and subjecting the load to mild agitation for a period in the order ofabout 3 minutes for each flush;

. washing said load in water at a temperature of about to about F. at a low water level for a period in the order of about 10 to about 15 minutes, said water containing a strong alkali at a concentration of about 0.2 to about 0.5 percent by weight of the dry weight of the fabric load and soap or a detergent;

4. flushing the load one or more times by introducing hot water at a temperature of about 160 F. to a high water level and subjecting the load to mild agitation for a period in the order of'about 3 minutes for each flush;

5. treating said load with an oxygen containing bleach which is hydrogen peroxide or a material which forms hydrogen peroxide or nascent oxygen in situ in admixture with hot water, said oxygen-containing bleach being present at a concentration level ranging from about 0.1 to about 0.2 percent by weight of the dry fabric load, said hot water being present at a medium water level while maintaining a temperature of at least about 175 F. for about 6 to about 10 minutes with mild agitation;

6. rinsing the load one or more times by introducing water at a high water level and subjecting the load to mild agitation for a period ofabout 3 minutes for each rinse;

.souring the load by introducing water at a temperature of about 110 F. to a medium water level; the souring agent being present in the range from about 0.005 to about 0.02 percent by weight of the dry fabric load and said water containing a water-soluble germicide at a concentration level sufficient to inhibit the growth ofmildew in the laundered fabric, and

8. extracting the water from said fabric.

13. The method of claim 12 wherein the temperature ofthe load is decreased during step (6) from the temperature em ployed instep by employing rinse water having a temperature which is intermediate to the temperatures of the water employed in steps (5) and (7).

14. The method of claim 12 wherein said oxygen-containing bleach is a peroxide.

15. The method of claim 12 wherein said oxygen-containing bleach is sodium-perborate.

16. A method for laundering fabrics to produce fabrics which are clean and substantially free from bacteria and bacterial spores comprising:

1. washing said fabric in hot water at a medium water level in the presence of soap or a detergent and a sequestering agent;

2. flushing the fabric one or more times;

3. treating the fabric load at a low water level at a water temperature of about 140 to 160 F. with an oxygen-com taining bleach which is hydrogen peroxide or a material which forms hydrogen peroxide or nascent oxygen in situ for a time sufficient to obtain substantially uniform penetration of the oxygen-containing bleach into the fabric load. the concentration of oxygen-containing bleach ranging from about 0.1 to about 0.2 percent by weight of the dry fabric weight;

4. increasing the temperature of the fabricload to about 175 to about 195 F. in the presence of a strong alkali and soap or a detergent and maintaining the increased temperature from about to about 15 minutes;

. flushing the fabric load one or more times;

7. extracting the water from the soured fabric load.

17. The method of claim 16 wherein the sequestering agent is present during step l of the process at a concentration in the order of about 0.01 to about 0.05 percent by weight of the dry weight ofthe fabric load.

18. The method of claim 16 wherein step (4) ofthe process is carried out in the presence of caustic soda.

19. The method of claim 17 wherein the strong alkali employed in step (4) is present at a concentration of about 0.2 to about 0.5 percent by weight of the dry weight of the fabric load.

20. The method of claim 19 wherein said strong alkali is caustic soda.

21. The method of claim 17 wherein the strong alkali employed in step (4) is present at a concentration of about 0.2 to about 0.5 percent by weight of the dry weight of the fabric load.

22. The method of claim 21 wherein said strong alkali is caustic soda.

23. The method of claim 16 including the use of a hypochlorite bleach step (5a) wherein the fabric load is agitated at a medium water level at a temperature of about Our F. for about 5 to about 7 minutes in the presence of a hypochlorite bleach in an amount effective to remove stains from the fabric load, said fabric load then being rinsed in step (512) before the souring step (6).

24. The method ofclaim 16 wherein said oxygen-containing bleach is a peroxide.

25. The method ofclaim 16 wherein said oxygen containing bleach is sodium perborate.

26. A method for laundering fabrics to produce fabrics which are clean and substantially free from bacteria and bacterial spores, said method comprising:

1. washing said fabrics in hot water at a temperature of about F.. said water containing soap and a sequestering agent, said sequestering agent being present at a concentration in the order of about 0.01 to about 0.05 percent by dry weight of the fabric load, and said washing step being carried out in a medium water level for a period in the order of about 3 to 5 minutes with mild agitation;

. flushing the load one or more times by introducing hot water at a temperature of 160 F. at a high water level and subjecting the load to mild agitation for a period in the order of about 3 minutes for each flush;

3. treating the fabric load at a low water level at a water temperature of about 140 to about 160 F. with an oxygen-containing bleach which is hydrogen peroxide or a material which forms hydrogen peroxide or nascent oxygen in situ, said treatment providing agitation of the fabric load for a period of about 3 to about 5 minutes to obtain substantially uniform penetration of the oxygencontaining bleach into the fabric, the concentration ofoxygen-containing bleach ranging from about 0.1 to about 0.2 percent by weight of the dry fabric weight; 4. increasing the temperature of the fabric load to about to about F. in the presence of a strong alkali at a concentration ofabout 0.2% to about 0.5% by weight of the dry weight of the fabric load and soap or a detergent. and maintaining the increased temperature for about 10 to about 15 minutes;

5. flushing the fabric load 1 or more times by introducing water at a high water level and subjecting the load to mild agitation for a period of about 3 minutes for each flush;

6. souring the fabric load by introducing water at a temperature of about 100 F. to a medium water level. the souring agent being present in the range ofabout 0.005 percent to about 0.02 percent by weight of the dry fabric load and said water containing a water-soluble germicide at a concentration level sufficient to inhibit the growth of mildew in the laundered fabric. and

7. extracting the water from said fabric.

27. The method ofclaim 26 wherein said oxygen-containing bleach is a peroxide.

28. The method ofclaim 26 wherein said oxygen-containing bleach is sodium perborate.

*zgz g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIGN Patent No. 3,650,667 Dated March 21, 1972 Inventor-(s) F n It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Lines 7 and 8, Column 2: The following is a mispr int and should be omitted:

"By way of example, medium soil items in the light soil category.

See specification, page 5, lines 15-20.

Omit page containing Column 14 with blank lines ll7. The page is duplicated with the omitted portion of Claims 3-8 supplied.

Signed and sealed this 2 +th day of April 1973.

(SJJAL) Attest:

EDWARD M. FLETCHER, JR. ROBERT GOTTSCHAiK Attesting Officer Commissioner of Patents 5g3 UNTTED STATES PATENT OFFICE QERTH ICATE OF QURREUHQN PatmnzNo. 3,650,667 Datmi March 21, 1972 lnventor(s) F.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown.below:

Lines 7 and 8, Column 2: The following is a misprint and should be omitted:

"By way of example, medium soil items in the light soil category."

See specification, page 5; lines 15-20.

Omit page containing Column 14 with blank lines l-l7. The page is duplicated with the omitted portion of Claims 3-8 supplied.

Signed and sealed this Zhth day of April 1973.

(SLLAL) Attest:

'EDWARD M FLETCHER, JR, RDBERT GOTTSCHALK Attesting Officer I Commissioner of Patents

Claims

2. flushing the load one or more times by introducing hot water at a temperature of 160* F. at a high water level and subjecting the load to mild agitation for a period in the order of about 3 minutes for each flush;
2. flushing the fabric load one or more times;
2. The method of claim 1 wherein the sequestering agent is present during step (1) of the process at a concentration in the order of about 0.01 percent to about 0.05 percent by weight of the dry weight of the fabric load.
2. flushing the fabric one or more times;
2. flushing the load one or more times by introducing hot water at a temperature of about 160* F. at a high water level and subjecting the load to mild agitation for a period in the order of about 3 minutes for each flush;
3. treating the fabric load at a low water level at a water temperature of about 140* to 160* F. with an oxygen-containing bleach which is hydrogen peroxide or a material which forms hydrogen peroxide or nascent oxygen in situ for a time sufficient to obtain substantially uniform penetration of the oxygen-containing bleach into the fabric load, the concentration of oxygen-containing bleach ranging from about 0.1 to about 0.2 percent by weight of the dry fabric weight;
3. treating the fabric load at a low water level at a water temperature of about 140* to about 160* F. with an oxygen-containing bleach which is hydrogen peroxide or a material which forms hydrogen peroxide or nascent oxygen in situ, said treatment providing agitation of the fabric load for a period of about 3 to about 5 minutes to obtain substantially uniform penetration of the oxygen-containing bleach into the fabric, the concentration of oxygen-containing bleach ranging from about 0.1 to about 0.2 percent by weight of the dry fabric weight;
3. The method of claim 1 wherein step (3) of the process is carried out in the presence of caustic soda.
3. washing the fabric at a low water level for about 10 to about 15 minutes at a temperature of about 175* to about 195* F. in the presence of a strong alkali and soap or a detergent;
3. washing said load in water at a temperature of about 175* to about 195* F. at a low water level for a period in the order of about 10 to about 15 minutes, said water containing a strong alkali at a concentration of about 0.2 to about 0.5 percent by weight of the dry weight of the fabric load and soap or a detergent;
4. flushing the fabric load;
4. The method of claim 2 wherein step (3) of the process is carried out in the presence of caustic soda.
4. increasing the temperature of the fabric load to about 175* to about 195* F. in the presence of a strong alkali at a concentration of about 0.2% to about 0.5% by weight of the dry weight of the fabric load and soap or a detergent, and maintaining the increased temperature for about 10 to about 15 minutes;
4. flushing the load one or more times by introducing hot water at a temperature of about 160* F. to a high water level and subjecting the load to mild agitation for a period in the order of about 3 minutes for each flush;
4. increasing the temperature of the fabric load to about 175* to about 195* F. in the presence of a strong alkali and soap or a detergent and maintaining the increased temperature from about 10 to about 15 minutes;
5. treating said load with an oxygen containing bleach which is hydrogen peroxide or a material which forms hydrogen peroxide or nascent oxygen in situ in admixture with hot water, said oxygen-containing bleach being present at a concentration level ranging from about 0.1 to about 0.2 percent by weight of the dry fabric load, said hot water being present at a medium water level while maintaining a temperature of at least about 175* F. for about 6 to about 10 minutes with mild agitation;
5. flushing the fabric load one or more times;
5. flushing the fabric load 1 or more times by introducing water at a high water level and subjecting the load to mild agitation for a period of about 3 minutes for each flush;
5. The method of claim 1 wherein the strong alkali employed in step (3) is present at a concentration of about 0.2 to about 0.5 percent by weight of the dry weight of the fabric load.
5. bleaching the fabric load in hot water at a medium water level with an oxygen-containing bleach which is hydrogen peroxide or a material which forms hydrogen peroxide or nascent oxygen in situ, said oxygen containing bleach being present at a concentration of about 0.1 to about 0.2 percent by weight of the dried fabric weight and the bleaching being carried out at a temperature of at least about 175* F. for about 6 to about 10 minutes;
6. rinsing the fabric load;
6. The method of claim 5 wherein said strong alkali is caustic soda.
6. rinsing the load one or more times by introducing water at a high water level and subjecting the load to mild agitation for a period of about 3 minutes for each rinse;
6. souring the fabric load in the presence of a souring agent and in the presence of a water-soluble germicide at a concentration level sufficient to inhibit the growth of mildew in the laundered fabric, and
6. souring the fabric load by introducing water at a temperature of about 100* F. to a medium water level, the souring agent being present in the range of about 0.005 percent to about 0.02 percent by weight of the dry fabric load and said water containing a water-soluble germicide at a concentration level sufficient to inhibit the growth Of mildew in the laundered fabric, and
7. extracting the water from the soured fabric load.
7. souring the load by introducing water at a temperature of about 110* F. to a medium water level; the souring agent being present in the range from about 0.005 to about 0.02 percent by weight of the dry fabric load and said water containing a water-soluble germicide at a concentration level sufficient to inhibit the growth of mildew in the laundered fabric, and
7. extracting the water from said fabric.
7. The method of claim 2 wherein the strong alkali employed in step (3) is present at a concentration of about 0.2 to about 0.5 percent by weight of the dry weight of the fabric load.
7. souring the fabric load in the presence of a souring agent and in the presence of a water-soluble germicide at a concentration level sufficient to inhibit the growth of mildew in the laundered fabric, and
8. extracting the water from the soured fabric.
8. The method of claim 7 wherein said strong alkali is caustic soda.
8. extracting the water from said fabric.
9. The method of claim 1 including the use of a hypochlorite bleach step (6a), wherein the fabric load is agitated at a medium water level at a water temperature of about 145* F. for about 5 to about 7 minutes in the presence of a hypochlorite bleach in an amount effective to remove stains from the fabric load, said fabric load then being rinsed in a step (6b) before the souring step (7).
10. The method of claim 1 wherein the oxygen-containing bleach is a peroxide.
11. The method of claim 1 wherein the oxygen-containing bleach is sodium perborate.
12. A method for laundering fabrics to produce fabrics which are clean and substantially free from bacteria and bacterial spores comprising:
13. The method of claim 12 wherein the temperature of the load is decreased during step (6) from the temperature employed in step (5) by employing rinse water having a temperature which is intermediate to the temperatures of the water employed in steps (5) and (7).
14. The method of claim 12 wherein said oxygen-containing bleach is a peroxide.
15. The method of claim 12 wherein said oxygen-containing bleach is sodium-perborate.
16. A method for laundering fabrics to produce fabrics which are clean and substantially free from bacteria and bacterial spores comprising:
17. The method of claim 16 wherein the sequestering agent is present during step (1) of the process at a concentration in the order of about 0.01 to about 0.05 percent by weight of the dry weight of the fabric load.
18. The method of claim 16 wherein step (4) of the process is carried out in the presence of caustic soda.
19. The method of claim 17 wherein the strong alkali employed in step (4) is present at a concentration of about 0.2 to about 0.5 percent by weight of the dry weight of the fabric load.
20. The method of claim 19 wherein said strong alkali is caustic soda.
21. The method of claim 17 wherein the strong alkali employed in step (4) is present at a concentration of about 0.2 to about 0.5 percent by weight of the dry weight of the fabric load.
22. The method of claim 21 wherein said strong alkali is caustic soda.
23. The method of claim 16 including the use of a hypochlorite bleach step (5a) wherein the fabric load is agitated at a medium water level at a temperature of about 145* F. for about 5 to about 7 minutes in the presence of a hypochlorite bleach in an amount effective to remove stains from the fabric load, said fabric load then being rinsed in step (5b) before the souring step (6).
24. The method of claim 16 wherein said oxygen-containing bleach is a peroxide.
25. The method of claim 16 wherein said oxygen-containing bleach is sodium perborate.
26. A method for laundering fabrics to produce fabrics which are clean and substantially free from bacteria and bacterial spores, said method comprising:
27. The method of claim 26 wherein said oxygen-containing bleach is a peroxide.
28. The method of claim 26 wherein said oxygen-containing bleach is sodium perborate.