Gravure Printing Cale Polkinghorne
Historical Background • Italian Renaissance 1300’s. • Engravings and etching into soft copper. • A channel or sunken area is left, this holds the ink. • Intaglio is the term used to describe gravure printing (Italian for printing in a sunken surface)
“Roto” Gravure • Roto means Round. • Term used for Industrial Intaglio. • Roto Gravure is printing from a cylinder. • Web Fed • Slitter ( devise used to cut sheets at the end of of the press)
Gravure Industry • Simplest of all printing systems. • Fastest press start up. • Very little paper waste (half the paper waste of lithography). • Speed is extremely high. • 45,000 copies an hour.
Gravure Industry (continued) • Some run 20 million copies without cylinder wearing out. • Highest quality image.
Industry Organization • 3 types of printing • Packing Printing • Publication Printing • Specialty Printing
Packaging Printing • This includes producing and folding. • Cartons • Boxes • Bags • Gift wrappers • Labels
Publication Printing • This includes Printing • Newspaper Supplements • Magazines • Catalogs • Mass Mailing Advertisements
Specialty Printing • Used to Print such materials as • Wallpaper • Vinyl • Floor covering • Textiles (decoration and clothing)
Methods of Cylinder Prep • Diffusion etch • Direct Transfer • Electromechanical Process • Laser cutting
Diffusion-Etch Process • Image exposed much like developing a plate for regular offset printing except negative in transferred. • Acid Bath • Copper cylinder • Cylinder then chromed (prolong life)
Direct-Transfer • Light Sensitive Mask • Acid Bath • Chrome plating
Electromechanical Process • Replaced chemical engraving • Basically Done by a computerized mill that etches a digitally scanned image.
Laser-cutting Process • Chemically etched holes are made. • Plastic is used to cover holes. • Same process as electromechanical is used except a laser does the cutting instead of a tool bit.
Well Formation • Gravure Transfers from small wells that are etched or cut in the cylinder • Cylinder rotates through a fountain of ink • Excess ink is wiped off by a doctor blade
Gravure Well Variables • Depth • Bottom • Opening • Bridge
Depth • Bottom of the well to the top surface of the cylinder
Bottom Obviously the bottom of the well
Opening • Distance across the well
Bridge • Surface of the cylinder between wells
Well Design • Conventional • Wells have exactly the same opening size • Amount of ink is controlled only by the depth of the well
Well Design (continued) • Lateral hard-dot • Can create half tone images • Well opening sized differ • Well depth stays the same
Cylinder Construction • Most cylinder cores are made of steel • Some companies prefer aluminum • Lighter • Less expensive • Easier to ship
Cylinder Design • Axis (center line of shaft) • Shaft (what the cylinder spins on) • Diameter • Circumference (one impression) • Face Length (printing width)
Two forms of Cylinders • Mandrel (removable shaft) • Integral (shaft mounted permanently) $$$$
General Info • An impression roller presses paper to Cylinder • Gravure printing allows high-quality images on low-grade papers.