Brown Paper

February 24, 2008 3:43 AM

Why do some types of paper (e.g. ski lift passes, recipts) turn brown when put through the dryer?
posted by charmston to science & nature (5 comments total)

They're heat sensitive. We have till rolls where I work that do this, but they go black. Ink isn't printed on them - it's a little heated "print head" that "burns" the covering on the paper, which leaves the mark. They're used because it's cheaper than using ink.
posted by Solomon at 3:45 AM on February 24

They are paper for thermal printing.
posted by grouse at 4:12 AM on February 24

Not only are they cheaper, but they don't run out of ink and slowly fade away and print invisible text for months until someone finally gets around to ordering new ink.
posted by PercussivePaul at 9:48 AM on February 24

Fax machines used to commonly use the paper as well, and entry level machines probably still do. The disadvantage with thermal paper is it often slowly fades over time. You should make a standard photocopy of any important receipt.
posted by 6550 at 10:44 AM on February 24

Same thing goes for many concert tickets. Losing your $150 tickets because you left them in the glovebox is no fun.
posted by Four Flavors at 3:12 PM on February 26