William Fox Talbot was one of the first people to take photographs, ‘painting with light’, although in the 1830s hours of full sunshine were needed. Thermal paper also needs a lot of energy to get a pic. But you won’t need to wait hours.
The simplest way to get a picture out of thermal paper is to rub it while it lies – sensitive side up – against an interesting, engraved surface. It’s that simple! The ‘magic’ is that the paper coating turns from clear to coloured when it gets to 100°C. The friction, of course, yields heat, and heat produces colour. It’s a bit like brass rubbing, where copies are made from artistic engravings by rubbing a stick of black wax over paper on the brass, but without the wax.
Most thermal paper is 40 or 60mm wide for receipt printers. Better is the A4-width paper for printers and faxes: £5-10 buys you a 30m roll of A4 width. Most turn black with heat, but there...