On demand useful life indicator

A useful life indicator comprising:

• a) a base member that is impermeable to a selected ambient fluid;
• b) an indicator material having a first side and an opposite second side, said first side being applied to one side of the base member in a predetermined pattern, said indicator material having a selected composition providing a visual indication when exposed to a predetermined active component of the ambient fluid;
• c) an adhesive applied with a predetermined pattern on a same side of the useful life indicator as the indicator material, said predetermined pattern of adhesive being applied to at least portions of the second side of the indicator material, said adhesive being impereable with respect to the active component of said ambient fluid;
• said predetermined pattern of the adhesive providing at least one void area that is absent adhesive therein said void area providing exposure of at least one selected portion of the indicator material to the active component of the ambient fluid;
• and
• d) a co-layered cover member that fully covers said adhesive and the indicator material, said cover member having at least two layers, a first layer of the two layers being impermeable to the selected ambient fluid for isolating said indicator material from the ambient fluid, a second layer of the two layers being permeable to the selected ambient fluid, and being positioned between the adhesive and the first layer said second layer having a greater attraction to the adhesive than to the first layer and said greater attraction resulting in said second layer being adhered to the adhesive for providing a membrane between the ambient fluid and the indicator material, the first layer being selectably removable from said second layer for completely exposing said second layer, thus enabling predetermined active component of the ambient fluid to permeate through the exposed second layer thereby equally and only exposing the selected portion of the indicating material interior of the void areas to the selected ambient fluid, to provide said visual indication said visual indication being observable through the exposed surface of the second layer, the visual indication beginning after removal of said first layer and being completed near the end of a predetermined period of time said membrane further providing abrasion protection for the adhesive and the indicator material during the predetermined period of time.