Offset printing is routinely used when print runs in excess of 500 are required for business cards, brochures, and even moderate size posters. To reproduce large quantities while maintaining consistent image fidelity, offset printing is used. The price per page reduces significantly as the number of pages increases. This is because most of the cost is consumed in the preparation of plates and color alignment (registration). Once set up, additional cost is essentially for materials and shipping.
In the process of offset printing, semi-transparent ink transfers from a thin metal plate wrapped around a drum onto a curved rubber roller. The inked roller, in turn, transfers images to a paper surface. This indirect, or "offset" method of printing is used in combination with the lithographic process, which is based on the repulsion of oil and water. Non-printing areas attract a water-based film (called "fountain solution"), keeping them free of ink.
High-speed offset web presses (not to be confused with the Internet) are typically used for magazine and newspaper production in excess of 10,000 impressions. Images are printed simultaneously on both sides of paper rolls (or "webs") and cut to desired sizes - usually inline by means of conveyor systems.
Sheet-fed offset presses print on stacks of pre-cut paper. This is ideally suited for print runs from 1,000 to 20,000 on one or both sides. Cost savings can be achieved by means of gang runs, where multiple share cost by printing jobs together on a large sheet. This method is employed where possible and reflected in quotes offered.
Offset quantities as low as 250 are available at nearly the same cost as 1000. Price breaks are achieved at quantities of 1,000, 2,500, 5,000, 10,000 and every 1,000 thereafter. It is more cost effective to request a standard quantity higher than needed and discard extra than to print a custom quantity.
Generally, offset printing reproduces images using the four-color CMYK process. Photographic mid-tones are converted to tiny dots within a pattern that simulates continuous tone photographs. Additional ink colors (usually Pantone) are sometimes added to maintain consistency of a dominant flat color without adversely affecting CMYK photos.
An integer separated by a forward slash indicates the number of colors used on each side of the page. Hence 4/0 represents CMYK with a blank back; 4/4 is CYMK both sides; 4/1 most often refers to black on the second side (though cyan, yellow or magenta may be used); 5/0 indicates a spot color has been added to traditional CMYK.