Lithography

Lithography This process uses a flat aluminum plate that works by mixing oil and water. By irradiating the negative film with ultraviolet rays, the image is transferred to the printing plate. The plate is then rinsed with chemicals to make the image area attractive for oily inks. The non-image area is then wetted with water to repel the ink. In order to prolong the life of the plate and prevent the paper from getting wet by coming into contact with water, the blanket transfers the ink from the plate to the paper.

Photolithography is the first method to print based on the immiscibility of oil and water. Printing from stone (lithographic limestone) or metal plate with smooth surface. Photolithography originally used images drawn with oil, fat or wax on the surface of a smooth, flat lithographic limestone slab. Treat the stone with a mixture of acid and gum arabic and etch the part of the stone that is not protected with a grease-based image. When the stones get wet then these etched areas retain water and oil based ink can then be applied and repelled by the water.

Offset lithography is an application of lithography in commercial mass production. The plate is not a stone but specially treated zinc or aluminum suitable for mounting on a cylinder. Take a picture of the lock board sensitized through the screen. The offset method includes double printing. The image from the plate is printed on a separate blanket covered roll and transferred from roll to paper. Since the image is inverted twice, the final printing corresponds to the original version. Since the photoresist ink is very thin, the hue region tends to lose some darkness and print gray, in order to speed up the ink and promote transfer. Litho offset printing is commonly used for color printing. Separated by photograph

In modern lithography, the image is made of a flexible plastic or a polymer coating applied to a metal plate. By printing the image on a flexible sheet (rubber) and printing it, you can print the image directly from the plate (reverse the direction of the image) or shift the image. As a printing technology, lithographic printing is different from lithographic or letterpress printing in which ink is applied to characters or images by gravure printing (gravure printing) that etches or stipples the printing plate to scribe the printing plate to accommodate the printing ink, and . On the surface. Today, most kinds of large books and magazines, especially color books, are printed in offset printing. This is the most common form of printing technology since the 1960's.