Each volume contained 50 plates engraved and etched by Merian. Titanium carbide can be etched with reactive-ion etching. Crystal faces are often etched and pitted with triangular markings. The metal foil is the material from which the circuit paths are normally etched. The surface is etched with acids, resulting in a surface of porous gold. The cathode foil is also etched to enlarge the surface. The sample can then be etched to reveal the microstructure and macrostructure of the metal. On his forehead he has etched a stylized image of a hydrogen atom. The tin/lead becomes the resist leaving the bare copper to be etched away. It contained 14 plates etched by the author. The initials "M+E" were etched on the same pillar. The end result is silicon that is etched anisotropically. Sculptor Dragon Dronet then etched designs into the blade by hand using dental tools. Diamonds may be etched by laser with marks invisible to the naked eye. Electrical contacts are deposited and then selectively etched away.