Most receipt paper is thermal paper: a standard paper base coated with heat-sensitive chemicals that produce text without any ink. When the printer’s heated elements touch the paper, the coating darkens to form letters and numbers. That’s why receipts feel smoother and glossier than regular paper, and why the print fades over time.
The Three Layers of Thermal Paper
A thermal receipt looks like a single thin sheet, but it’s built from three distinct layers working together. The bottom layer is ordinary wood-pulp paper, similar to what you’d find in a notebook. On top of that sits a pre-coat (sometimes called a base coat), which creates a smooth, even surface and prevents heat from bleeding through the entire sheet. This layer is what gives receipts their characteristic slick feel compared to standard printer paper.
The top layer is where the chemistry happens. This thermal reactive coating contains two key ingredients suspended in tiny particles: a colorless dye and a chemical developer. At room temperature these two substances are kept apart by a waxy binder. When the print head of a thermal printer applies a precise burst of heat, the wax melts, the dye and developer come into contact, and the dye shifts from colorless to black (or sometimes blue). The whole reaction takes a fraction of a second, which is why receipt printers are fast and nearly silent.
The Developer Chemical Matters
The developer is the ingredient that has drawn the most scrutiny. For decades, the standard developer in thermal paper was bisphenol A (BPA), a synthetic compound that mimics estrogen in the body. BPA made up a significant portion of the thermal coating’s weight and sat right on the surface of every receipt.
That’s changed substantially. A 2023 analysis of U.S. receipts found that bisphenol S (BPS) had become the most common developer, present in 85% of tested receipts. Only about 1% of receipts still contained BPA, down sharply from earlier years. About 12% used a non-bisphenol alternative called Pergafast 201, and a handful of newer compounds appeared at low frequencies. National retailers were more likely than local businesses to have switched away from bisphenols entirely.
The shift away from BPA was driven partly by regulation. The European Union restricted BPA in thermal paper starting in January 2020. Several U.S. states passed similar measures. But the switch to BPS has raised its own questions, since BPS is structurally similar to BPA and its long-term health profile is still being studied.
How BPA Gets Into Your Body From Receipts
Because the developer chemical sits in the outermost coating, it transfers to your skin on contact. A lab study measuring skin absorption over 24 hours found that about 25% of BPA applied to skin was absorbed. BPS, by comparison, had a much lower absorption rate of around 0.4%. Pergafast 201 was absorbed at levels too low to reliably measure. So the type of developer in your receipt directly affects how much chemical exposure you get from handling it.
Absorption increases when skin is wet or oily, which is why hand sanitizer before handling receipts has been flagged as a concern in some research. Cashiers and others who handle receipts all day accumulate more exposure than someone grabbing one receipt at the grocery store.
Why Receipts Don’t Belong in the Recycling Bin
Thermal receipts create a contamination problem when they enter the paper recycling stream. The BPA or BPS in the coating doesn’t disappear during recycling. Instead, it spreads into the recycled pulp and ends up in other products. BPA has been detected in recycled toilet paper, for example, which then enters wastewater systems where it doesn’t fully break down. BPA can also be discharged directly into surface water during the recycling process itself.
For this reason, many recycling programs ask you to throw receipts in the trash rather than the recycling bin. Some newer “phenol-free” thermal papers are marketed as recyclable, but unless you know the specific chemistry of a receipt, the safest default is to keep it out of your recycling.
How to Tell if Paper Is Thermal
The simplest test is the scratch test. Drag your fingernail firmly across the paper’s surface. If a dark mark appears where you scratched, it’s thermal paper. The friction generates just enough heat to trigger the same chemical reaction the printer uses. Try both sides: if neither side darkens, you have regular paper printed with conventional ink.
You can also look for visual cues. Thermal paper is noticeably shinier and smoother than standard bond paper or carbonless copy paper. Another method is to hold a lighter briefly near the back of the paper (without igniting it). If the paper changes color and the discoloration gradually fades toward the edges, it’s thermal. And if you feed a piece of regular printer paper through a thermal receipt printer, nothing will print at all, since there’s no reactive coating to respond to the heat.
Not All Receipts Are Thermal
While the vast majority of point-of-sale receipts use thermal paper, some businesses still use impact printers with ink ribbons, particularly for multi-part receipts where a carbon copy is needed. These receipts feel rougher, the print doesn’t fade, and the scratch test won’t produce a mark. Credit card slips at some restaurants, shipping labels, and certain ATM receipts may also use non-thermal paper. If you’re trying to reduce chemical exposure from receipts, knowing the difference lets you make practical choices about which ones to handle and which to decline.