Lithografia

Lithography is a printing process based on the immiscibility of oil and water, and on the principle that grease and water repel each other. It is a planographic method, meaning the printing surface remains flat throughout the process. The image areas are treated so they attract ink, while the non-image areas hold water and repel ink.

The method was invented by Alois Senefelder in 1796 in Bavaria and originally relied on drawing on polished limestone. It spread in the 19th century and became widely used for art prints, posters, and book illustrations. In the 20th century, offset lithography emerged and displaced direct lithography for many commercial applications, enabling higher speeds and mass production.

In traditional lithography, an artist or technician draws the image on a stone or metal plate with a greasy material. The surface is then chemically processed to create ink-receptive image areas and water-receptive non-image areas. The plate is moistened with water and rolled with ink; the greasy image areas attract ink while the damp non-image areas repel it. Paper is pressed against the plate to transfer the inked image. For color work, multiple stones or plates are used, one for each color.

Modern lithography includes offset lithography, in which the image is transferred from the plate to a rubber blanket and then to paper, enabling efficient high-volume printing. Advances in lithography also include computer-to-plate workflows and digital imaging. In semiconductor manufacturing, lithography refers to photolithography, a process that uses light to transfer circuit patterns onto a substrate, a key step in fabricating integrated circuits. Materials for traditional lithography have shifted from carved limestone to metal and synthetic plates.