A label comprising, on the one hand, a coloring substance of the type that has the ability to produce an impression by the effect of heat, whose printing color contrasts with the base color of the label, and on the other hand, an agent that has the objective of, at least partially, destroying the contrast between said colors, if the label is exposed to a temperature above a predetermined maximum value, the label having a surface for a print (3) containing the encoded information, characterized because it is made of a porous capillary absorption substrate (5) that includes said impression (3) and because said agent is included in a charge of a substance (7), which is solid at temperatures up to said maximum value, but becomes liquid above it, and whose load on said substrate is located next to the printing surface field (3).
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