The researchers coated the cotton fibers by dipping them in a few different solutions—first, an acidic solution of tin chloride to sensitize it, then a palladium salt solution to give it a layer of palladium. The silver or copper molecules in the third solution stick onto the palladium molecules. Within six minutes, 12 milligrams of copper and silver stuck onto a piece of fabric that was four square centimeters in the researchers’ experiment. The copper made the fabric look a bit reddish, the silver made it look brownish-black, the study authors write. When the scientists deposited some organic molecules on the fabric, the copper coating performed much better in the dark, eliminating the organic molecules in five minutes (the silver coating took 45 minutes). Under visible light, the copper-coated fabric finished its reaction in three minutes, the silver in 30. But after exposing the material to organic compounds 15 times, the silver coated fabric performed better.