Search results
Results from the WOW.Com Content Network
Offset printing is a common printing technique in which the inked image is transferred (or "offset") from a plate to a rubber blanket and then to the printing surface. When used in combination with the lithographic process, which is based on the repulsion of oil and water, the offset technique employs a flat (planographic) image carrier.
The problem can occur with most types of printing, and is avoided by the use of slipsheets between copies (so any ink transfer occurs onto discardable paper) or anti-set-off spray powder. The term in offset printing also refers to the unwanted transfer of ink to rollers and friction points throughout the printing press. Ink that is not properly ...
Waterless printing yields higher ink densities and a broader color spectrum than conventional offset printing does. Waterless plates used on sheet-fed presses are commonly rated for runs of 100,000 to 200,000 impressions. The plates designed for use on web-offset presses can yield 300,000 to 500,000 impressions.
[8] [9] Offset printing or "offset lithography" is an elaboration of lithography in which the ink is transferred from the plate to the paper indirectly by means of a rubber plate or cylinder, rather than by direct contact. This technique keeps the paper dry and allows fully automated high-speed operation.
Letterpress printing was the normal form of printing text from its invention by Johannes Gutenberg in the mid-15th century and remained in wide use for books and other uses until the second half of the 20th century, when offset printing was developed. More recently, letterpress printing has seen a revival in an artisanal form.
Offset printing replaced chromolithography in the late 1930s. To find or purchase a lithograph, some suggest searching for examples with the original frame as well as the publisher's stamp. [ 18 ] Both European and American chromolithographs can still be found, and can range in cost from hundreds to thousands of dollars.
It is crucial that offset ink resist water-in-ink emulsification (i.e., repel rather than absorb water). It also should withstand degradation by the fountain solution that covers the non-printing areas of the engraved plate. Offset ink needs to be very rich in pigment so that its full color vibrancy is perceptible, even in minute quantity. [2] [3]
McBrayer is best known for inventing the Vanguard web offset press for newspaper printing. [2] [3] After five years of effort and experimentation, he ultimately succeeded in modifying an offset printing press designed for book printing and adapting it for printing newspapers: the result was the Vanguard web offset press, which he unveiled in 1954 in Fort Worth.