The present invention discloses a time passage indicating apparatus which comprises a substrate, a background layer on the substrate, and a time passage indicating layer on the background layer. The background layer and the time passage indicating layer bond to each other through a first and second polymer...http://www.google.es/patents/US7974157?utm_source=gb-gplus-sharePatente US7974157 - Method for forming an apparatus for indicating the passage of time and the formed apparatus
Method for forming an apparatus for indicating the passage of time and the ...
