Patent ID: 8092315

Claim:
An apparatus comprising: a substrate layer having a first side and a second side, the first side to engage a surface of a first object; and at least one thermochromic compound layer overlaying at least first and second surface portions of the second side of the substrate layer to generate a set of temporary marks; wherein: the at least one thermochromic compound comprises a layer comprising: a first thermochromic compound; and a second thermochromic compound different than the first thermochromic compound, the first thermochromic compound overlays the first surface portion without overlaying the second surface portion; the second thermochromic compound overlays the second surface portion without overlaying the first surface portion; the second thermochromic compound is disposed proximate to and in direct contact with at least part of the first thermochromic compound; the first thermochromic compound comprises a first thermochromic color at a first temperature; the second thermochromic compound comprises a second thermochromic color at a first temperature; while the first and second thermochromic compounds are at the first temperature, a contrast between the first and second thermochromic colors defines a pattern over the substrate layer; the set of temporary marks is configured to comprise: a first temporary mark at a first impact location associated with a first impact over the surface of the first object by a second object; and one or more subsequent temporary marks at one or more subsequent impact locations associated with one or more subsequent impacts to the surface of the first object; the at least one thermochromic compound is configured to be in direct contact with the second object during at least the first impact such that at least one of the first or second thermochromic compounds directly contacts the second object; the thermochromic compound is configured to enable the first temporary mark to: fade throughout a fading period accommodative of the one or more subsequent impacts; and remain distinguishable throughout the fading period from the one or more subsequent temporary marks; the apparatus is reusable after the one or more subsequent impacts to indicate further impacts via further temporary marks after the first temporary mark and the one or more subsequent temporary marks have completely faded away; and the apparatus is devoid of a protective barrier between the thermochromic compound and the second object during the first impact.