Scan your faded thermal paper as a colored photo and then use your photo editing software's special effects tools to create a negative image—a black image featuring the faded print outlined in white or completely white. In your open image, select any tool option titled "Negative" or "Create a negative," and then use any other enhancement features to make the whitened original print information clearer. For example, adjust the level of contrast or smooth or sharpen the print on the image.
Use a hair dryer to create a "negative" image if tweaking a scanned copy of your thermal paper didn't restore the print information. Turn on your hair dryer and lightly blow heat over the back of the faded thermal paper that you hope to restore. Hold the hair dryer at least 8 to 12 inches from the away from the surface to protect against rapid darkening that could cause the original thermal print information to blacken completely.
If you don't have a hair dryer, use a light bulb, but hold the paper approximately 2 to 5 inches from the light bulb depending on the level of heat the bulb generates.
Save a copy of your restored thermal paper document for your records and store the original hardcopy in a cool, dry place away from UV light, water or chemicals.