What is actually on a thermal receipt
Thermal paper has no ink. The image comes from a chemical coating — and which chemical that is has been argued about for twenty years.
Hold a shop receipt up to a light and you will notice it is slightly glossy on one side. That coating is the reason the receipt exists. Thermal paper carries no ink: the printer applies heat, and a layer of dye and developer on the surface reacts and turns black.
The dye is not usually the interesting part. The developer is.
The developer question
For decades the most common developer in thermal paper was bisphenol A — BPA. It is cheap, it works, and it sits on the surface of the paper rather than being bound into the fibre, which means it can transfer to skin on contact.
This became enough of a concern that the European Union restricted BPA in thermal paper: since January 2020, thermal paper placed on the EU market may not contain BPA at or above 0.02% by weight. That is a real regulatory action, taken under REACH, and it is the clearest signal available about how the question was eventually judged.
Much of the industry moved to bisphenol S — BPS — instead. Whether that is meaningfully better is genuinely contested, and we are not going to tell you it is settled, because it is not. What we will say is that the argument has been running for twenty years and shows no sign of ending.
We are not claiming receipts are dangerous. We are pointing out that twenty years in, the industry still cannot agree on what to coat them with.
Who touches them most
A customer handles a receipt for a few seconds. The person behind the counter handles every receipt, all day, every day. If there is an exposure question here at all, it belongs to the shopkeeper and the cashier far more than to the customer.
That is worth stating plainly, because the people who would be most affected are the people this software is built for.
The part nobody argues about
Set the chemistry aside. Two things about thermal receipts are simply true and not disputed by anyone.
- They fade. The image is a chemical reaction, and heat, sunlight and time undo it. A receipt kept in a drawer for a warranty claim or a tax record may be blank when it is needed — which makes thermal paper a poor way to keep a record you actually rely on.
- They are difficult to recycle. The coating is a contaminant in the paper stream, so thermal receipts are commonly excluded from normal paper recycling and go to waste instead.
What we do instead
A PepulBill bill opens on the customer's phone. It does not fade, it can be opened again next month, and there is nothing to dispose of. The shopkeeper never handles a roll of anything.
We did not build it that way because of BPA. We built it that way because a printer is a machine a small shop should not have to buy. But of all the things we removed, this is the one we are most comfortable having removed.