Thermal paper, commonly used for receipts, has a chemical that changes color when sunlight or heat comes in contact with it, causing the print on the receipt to fade. Keeping your receipts in a temperature-controlled location with no direct sunlight might help to slow the fade. At best, however, this only delays the fading process and doesn’t prevent receipts from fading entirely. We have found that the surest way to preserve receipts is to scan them.