What is the difference between copying (e.g. Xerox) technology and offset printing?
Copying, or xerography, involves creating a magnetic image on a photo drum using a laser beam. The magnetic field then attracts staticly charged toner particles which are then deposited on to the page. Once the image is on the page, the toner is run past a fuser unit to melt it onto the page. With offset printing, an image is photographically etched on to an aluminum, plastic or paper plate which is then mounted onto a drum. Water is then applied to the plate so that the liquid ink is repelled from the areas without an image and attracted to the areas with the etched image. The inked plate is then pressed onto a roller which applies the ink to the paper. Since offset printing involves a fair amount of preparation work for each image, the main difference between the two technologies comes down to cost and volume. Copier or laser technology is cost effective for short runs of up to about 1,000 pages. Offset printing starts to become cost effective for quantities larger than that. Can you
