Direct thermal labels use the heat from the printer’s printhead to activate the special chemical coating on the label. This then transforms areas on the label to being black, in order to make the required image.
Direct thermal labels tend to fade over six to 12 months. If exposed to heat, direct sunlight or chemical vapours, their life can be shortened further. Direct thermal labels are therefore often used as shipping labels or for labelling fresh food, when longevity is not important.
Direct thermal labels adhere to most standard surfaces, including plastic, metal, cardboard and films, but are not suitable for areas of moisture, grease or scuffing.