Not all commercial printers offer this option.
A similar but much quicker and more efficient process called photogravure is used commercially to produce large volumes of high-quality prints. German actor and writer Alois Senefelder invents lithography, the water-and-grease printing process used in modern offset printing.
In practice, newspapers use much smaller dots than this—we've exaggerated greatly so you can see how it works. But what about lithography? Things become more complicated when color photos are involved.
A hands-on guide to printing from first principles. Silver halide plates can be exposed either photographically or by lasers guided by computer data. The burden of producing printing plates fall on the printer.
Lithography literally means "stone-writing," a method of printing from the surface of stones that was invented in 1798 by German actor and playwright Alois Senefelder. Printing plates are usually made from metal, plastic, rubber, paper, and other materials.
Richard March Hoe develops the rotary press for newspaper printing and later perfects it so it can print on both sides of the paper at up to 20,000 pages per hour. Light sensitive, diazo photo-polymer pre-coated aluminium printing plates are now the predominant plates in print shops. Printing in color costs much more than printing in black-and-white, for various reasons.Intro Platemaking
The process can be repeated any number of times. Modern offset lithography printing presses use an updated version of the same basic idea in which the stone is replaced with a thin metal printing plate. Steve Jobs launches the Apple Macintosh computer loosely based on the earlier Xerox Alto , which, partnered with a compact and relatively affordable laser printer, begins a revolution in desktop publishing.
He took a large stone and drew a design on it with a wax crayon. This involves covering the article to be printed something like a blank cotton shirt with a mesh-screen and a stencil, then wiping ink over the mesh with a brush.
That's why most letterpresses use rotating cylinders in place of one or both of the flat beds. These utilise two separate coatings, a conventional photopolymer as the bottom layer, a silver halide coating providing the top layer. Scott Crump of Stratasys pioneers the modern approach to 3D printing called fused deposition modeling bulding up a 3D object from hot plastic, layer by layer.
Of primary advantage to these plates is their virtual indestructibility. All offset presses have three printing cylinders plate, blanket and impression , besides inking and dampening systems.