Handwritten labels on garden plants are usually unreadable after a few weeks outside. Rain dissolves cardboard and washes ink off plastic, and sunlight fades what鈥檚 left. The answer, according to Danish company Brandsoft, is to laser-print the label on a special plastic sheet, and take advantage of the high temperatures normally used to fuse the toner to make the message indelible (WO 03/012764).
Brandsoft鈥檚 polyolefin plastic sheet is designed to be fed into a printer instead of paper. The surface of the sheet is peppered with sub-micrometre pores, and the 250 掳C temperatures used in the fuser unit help the toner penetrate the pores, where they are trapped as the plastic cools. Brandsoft鈥檚 tests show labels made this way survive years of rain and sun.