Many colours dry darker once printed, and can also change shade depending on the substrate, the mesh count, and the amount of thinners or base added to the ink. Always pretest when colour matching is critical. New processes and products are constantly being invented using this technique. The pine oil burns off when the material is fired, the frit melts and bonds to the surface, and the pigments produce different colours. This is known as enamelling when used on metal.
Acids are mixed with a paste and then printed on metals or glass.
The acid eats the surface, and when the etching process is complete, the acid is washed off. Shower doors, decorative glass, jewellry, mirrored glass in pinball machines and some circuit boards are produced this way. Conductive metals such as silver, nickel, and gold are mixed with a carrier that will stick to lexan or other thin plastic films. An actual circuit is printed on the material, and then the material is layered with other plastics to encase the circuit. Membrane switches, back window heaters, radiant heating panels, and those new Duracell battery testers are typical uses of this process.