[cocothem]

What about the ink? What's the keyword to search for nom toxic printer ink/cartridge

[rozab]

Receipt printers don't use ink, instead they use thermal paper which darkens when heated. You can test this by scratching it with your nail, the heat is enough to leave a mark

[gaudystead]

I agree with you on the first part, but are you sure that the heat from the fingernail is what's leaving that mark? I can take a cold object and run it on the receipt paper to get the same effect, so I think that's a different mechanism at play but I'm open to being proven wrong.

[joseda-hg]

I thought most receipt printers were thermal, no ink, just heat