Why do receipts fade, and how do you keep them readable?

Most receipts aren't printed with ink at all. They're thermal paper: the paper's coating contains a colourless dye and a developer, and the printer simply heats them so they react and turn black (US EPA, Bisphenol A Alternatives in Thermal Paper). Nothing is added to the page. The page itself changes colour.

That's why receipts fade: the printed image is a chemical state, not a pigment. Over time the reaction slowly reverses: the dye and developer separate again, and the text literally un-prints. Every faded receipt in your glovebox is doing this right now.

What speeds it up

• Heat. The coating reacts at roughly 45–65 °C, a temperature a parked car or a sunny windowsill reaches easily. Heat can also do the opposite and turn the whole receipt black.
• Sunlight and UV. Extended light exposure degrades the image and yellows the paper.
• Plastic, tape, and sleeves. Plasticizers in PVC sleeves and the adhesive side of tape react with the coating. Taping a receipt into a notebook or filing it in a vinyl pocket actively erases it.
• Alcohol and oils. Solvents (including hand sanitizer) plus lotions and skin oils dissolve or smear the image.
• Friction, water, and other receipts. Rubbing develops grey marks; moisture degrades the coating; even storing receipts face-to-face can transfer chemistry between them.

How long do receipts really last?

Honest numbers, from people who preserve documents for a living:

• The US National Archives warns thermal images "may begin to deteriorate in as few as six months" (NARA Bulletin 96-03).
• The UK National Archives says text on thermal paper "can disappear within a period of only a few years" under ordinary storage (thermal paper guidance).
• Manufacturers quote 5–10 years, but only in dark, cool, plastic-free archival storage that no wallet, drawer, or shoebox provides.

Meanwhile, the CRA can ask you to back up a claim six years after the tax year it relates to. The math doesn't work in paper's favour: for a receipt that must survive to year six in a shoebox, the realistic expectation is a blank strip of paper.

Can you bring a faded receipt back?

Sometimes, briefly. Gently warming the back of a thermal receipt (a hair dryer at a distance) can re-develop residual chemistry and make the text ghost back. But it's a one-shot trick that can just as easily turn the entire receipt black. If you try it, photograph the receipt first, and treat anything you recover as a bonus. Prevention beats resurrection.

What actually preserves a receipt

1. Photograph it immediately. The moment of purchase is the receipt's most legible moment; it only degrades from there. The CRA accepts properly captured images as permanent records in place of the paper.
2. If you must keep paper: cool, dark, and dry; paper envelopes or folders, never PVC sleeves; no tape on the printed side; don't stack print-against-print.
3. Never laminate. Heat plus plastic is the double kill.

The takeaway

Thermal receipts are engineered to be cheap at the till, not to survive an audit window. The only reliable preservation strategy is getting the information off the paper while it's still readable. Today that means a photo, taken at the counter, stored somewhere it can be found six years later.