[WalterBright]

> The reactant in thermal paper is often BPA.

Too bad. The original "invisible ink" activated by heat is lemon juice.

[TheSpiceIsLife]

I heard this before, but how does that knowledge help with dealing with BPA exposure now?

[WalterBright]

Obviously, it doesn't. But the knowledge of lemon juice is something you can pressure your thermal printer vendor with.

[int_19h]

Or milk.