Thermal labels print without ink: a coating on the paper reacts to the heat of the printhead and turns dark. That coating contains a developer, and the developer is what buyers are now asking about.

BPA (bisphenol A) has been the standard developer in direct-thermal paper for decades. It is also the substance that made receipts a regulatory topic in Europe and, more recently, a specification item in ordinary purchase orders. This page explains what the claim covers and how to specify it without overstating it.

Where BPA sits in a thermal label

There are three layers to separate: the base paper, the thermal coating — which holds the developer and the dye — and the adhesive. BPA is a question about the thermal coating. A label can be BPA-free and still carry a solvent-based adhesive, or a recycled face containing other substances, which is why the requirement belongs to a layer rather than to a product name.

Why buyers started asking

Receipts and labels are handled directly, sometimes for hours a day, and then discarded into a waste stream that is increasingly separated and recycled. Two things followed: restrictions on BPA in thermal paper in the EU, and retailer specifications that go further than the regulation. Once a large buyer writes “BPA-free thermal” into a specification, it travels down the chain to anyone printing a shelf label.

Three claims that are not the same

This is where quotations usually get confusing:

  • BPA-free — no bisphenol A in the thermal coating.
  • BPS-free — no bisphenol S. BPS was the common replacement and is now restricted in the same contexts in Europe.
  • Phenol-free — no phenolic developer of any kind. The widest claim, and the hardest to support.

A supplier who answers yes to one of these has not answered the other two. Ask which one is being claimed, on which layer, and against which test method.

How to word the requirement

  • Put the requirement on a layer: thermal coating, adhesive or face stock.
  • Name the claim you need: BPA-free, BPS-free or phenol-free.
  • Say what the label touches: bare hands, food packaging, or a surface recycled with the label attached.
  • Ask for the declaration per batch, not per product family.

What to do with the answer

A declaration is only useful if it names the substance, the limit and the method. Where a phenol-free grade is needed, settle it before the artwork is approved: changing the coating afterwards usually means re-testing print density and image life, because the developer and the coating system change together.

FAQ

Is BPA-free the same as food-safe?

No. Food contact is a separate question about the whole construction, adhesive and liner included, and it is answered by a migration assessment rather than by the absence of one substance.

Does a BPA-free coating print as dark?

Print density depends on the coating system, not the developer alone. Confirm density and barcode grade on the specific grade rather than assuming a difference.

Does image life change?

It can. Developer chemistry affects how the image ages under heat, light and plasticiser contact. Ask for the reading period on the grade you are buying.

Related: White thermal labels · Triple-proof thermal labels · Thermal receipt paper