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 to 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 to 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.

When heat develops the whole strip

Heat developed it. If that is what you are looking at right now, the full answer, including whether the expense is still claimable, is on the receipt turned black page. The same coating that turns black at roughly 45 to 65 °C in the printer develops anywhere that heat reaches it later: a dashboard in the sun, a radiator, a laminator, or an iron can develop the whole strip at once, so the receipt goes dark or fully black.

Be honest with yourself first: if the strip is fully black, the chemistry has fully developed and the original text is not coming back. If it is dark but you can still see ghosts of text, work down this list before giving up:

1. Stop adding heat. No hair dryer, no iron, and never a laminator: the heat that seals the pouch is the same heat that blackens the paper.
2. Photograph it under raking light. Hold a lamp or your phone light almost level with the paper so the surface texture casts shadows, and shoot from an angle.
3. Push the contrast, then view it inverted. In your phone's photo editor, drop the exposure and raise the contrast. To view the result inverted (faint grey text is easier to read as light on dark), use the accessibility setting rather than the photo editor: on iPhone it is Settings, then Accessibility, then Display & Text Size, then Classic Invert. Full step by step here.
4. Try a photocopier on its darkest setting. The cheapest office trick: copiers exaggerate whatever contrast is left.
5. UV light is a long shot. A 365 nm blacklight can make some thermal coatings fluoresce so text stands out. It is a real forensic technique, but results on home receipts are mixed, so treat anything it recovers as a bonus.

If it cannot be recovered

Treat it like a missing receipt, and build the fallback evidence the CRA itself points to: ask the vendor for a duplicate or reprint, keep the card or bank statement as proof of payment, and record the seller, date, amount, and details in an expense journal (CRA: business records). Remember the stakes: records need to survive six years from the end of the tax year they relate to, and the CRA accepts a clear photo as the permanent record, which is why the real fix is capturing the image before the paper ever gets the chance to turn.

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. For the full triage, including which receipts are worth attempting and what to do when the text is gone, see how to read a faded receipt.

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.