If you go to the banks in Taiwan, or you pay a bill at 7-11, or put money on your Easycard, you always get a little slip of paper that fades in about 4 weeks. These are supposed to be receipts but something about the humidity seems to make the ink dots fade rapidly.
I remember first coming across thermal paper when I was lusting after the infamous ZX-81 mini pc that came with a 16KB memory pack and printer, if you ponied up the extra cash.
So I was surprised that 30 years hadn’t seemed to improve the thermal printing. It seems that thermal printing is still widely used as testified by its continual use in POS systems in 7-11. Even Epson still produces uptodate printers like the tm-t88iv for the POS market, and they are NOT cheap compared to inkjet or laser printers.
I guess they must be pretty reliable. I’ve never seen one break down. But I’m dubious about claims like “thermally-printed text should remain legible at least 50 years”. I think 50 days would be too much in Taiwan.
If you want to keep the data, you should either photograph, scan or photocopy the data on the receipt. It just doesn’t keep well.