Disappearing Ink on Thermal Paper?

dpippenger asks: "A few days ago my rear projection TV made a soft clicking noise and the color balance suddenly went a bit blue. The set was only about 3 months old and I neglected to get the in store warranty. I decided to try and cash in on the 1 year manufacturers warranty which only required an original sales receipt as documentation. I quickly opened up my file cabinet and retrieved the receipt in question. I was fairly upset to find the sales receipt was printed on a slippery thermal paper (pretty common these days) and after only 3 months was noticeably degraded. The paper was discolored slightly and important blocks of text like the model number were just gone. After some conversation at the TV repair shop they finally accepted it as proof of warranty. The problem is this receipt is my only evidence of warranty for an entire year. I have to wonder what the receipt will look like in another 9 months and if it will be unacceptable as proof of purchase next time I need repairs. Have any other readers had a similar experience or have tips on preserving these thermal receipts?"

Not good enough

[droyad]

Demand a non-thermal reciept for anything your going to keep longer than a week. Remember the law (at least here) says that you have to keep your reciepts (that you claim on tax) for at least 7 YEARS. This means that the Tax Office can after 7 years demand to see what you have claimed and they would be mighty pissed off if all the reciepts were blank.