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How to activate thermacare heat wraps
Unwrap the heat wrap thirty minutes before use.
The chemical ingredients in thermacare wraps need to be exposed to air to activate. Once exposed to air, the wrap should immediately begin heating, reaching its maximum temperature in about half an hour.
Attaching the wrap too early will limit its exposure to air, causing it to heat more slowly. Do not microwave the wrap, or attempt to speed up the warming by heating it in any other fashion.