Simply put, waterless printing is an offset printing process that prints without water. Offset printing is the most common production printing method in use today—as much as 40% of all printed material you see, touch and consume on a daily basis is produced using offset printing.
Offset printing is traditionally a lithographic process that requires two different fluids (ink and water) to transfer an image from plate to paper. Developed in the 1790s by Alois Senefelder, lithography originally used a specially prepared, flat limestone surface, on which an image was formed with a greasy crayon. The stone was then wetted in the non-printing area with a solution of water and gum arabic. An oil-based ink was applied and was resisted by the water in the background, but adhered to the image area. Finally, paper was pressed to the surface of the stone and the inked image was transferred to the paper. The term lithography literally means “stone printing,” from the Greek lithos (stone) and graphos (to write).
So, what does all this ancient history have to do with offset lithography today? For starters, although the materials have changed (we don’t use rocks anymore), the basic principle is still the same. In today’s conventional lithography, an aluminum plate is employed that has a surface that is specially grained to attract water. An image is formed on the plate in a polymer coating that has properties to attract ink and resist water. During printing, the background of the plate is wetted and ink is applied. Senefelder’s 220+-year-old principle that oil and water don’t mix still governs the process. Note that working with two fluids—each with very different properties—can be a complex process, especially in today’s high-speed offset presses.
Waterless printing eliminates the need for water in the printing process by using a special printing plate that has only two surface properties—ink-resistant and ink-attractive. By working with only one fluid—ink—as opposed to two fundamentally different fluids—ink AND water—the printing process is greatly simplified and some very unique benefits can be realized.