Printing press plates are used to transfer text and images to the item to be printed. Plates come in many forms, depending on the printing process used, and are required for every new print job.
Types of printing plates vary according to the press used, but can be classified by direct or indirect ink transfer. Direct plates transfer ink directly to the item to be printed. Indirect plates transfer ink to a "pad" or "blanket" carrier, which is then pressed against the item.
Plates for many printing processes use a photographic method, where a picture is taken of the text and design with a graphic arts camera. The image is transferred directly to the photographic plate or via a film developing process. Some plates are imaged directly from computer plate makers, while others are machine- or laser-engraved.
Plate making is usually included in the print price, amortized according to the quantity of items printed. Plates require labor and materials to produce and set up, which is why small quantities of printed products can be cost-prohibitive.
Number of Plates
Printing plates are able to print one ink color at a time. Multicolor print jobs require a separate plate for each ink color used.
All printing plates have a limited useful life. Depending on the type of plate and printing process used, some plates may be reused for future repeat jobs. Inexpensive paper or plastic plates, used primarily by "quick" printers, can only be used once.
Although customers often pay for plates, the charge incurred is usually for labor costs. Plates that can be reused are normally retained by the printer, who exercises ownership rights to protect future business interests.
- Image by Flickr.com, courtesy of Jeremy Keith