Types of prints

Relief Prints

Relief prints can be made from a variety of materials; wood, cork, linoleum, found objects, anything that can pick up color and transfer it to another surface. Linoleum is a stable relatively soft material that can be easily cut with gouges and knives. In Linoleum printing, an image is cut into its surface, water or oil-based ink is applied to it, and paper is pressed on to it so that the image is transferred to the paper.

The image printed is a mirror image of the one that was cut into the linoleum block; so the printmaker, once an image has been planned, must reverse the image before cutting it into the block to have the image facing the way he intended. The technique is similar to that of a potato print or rubber stamp. Wood cuts and wood engravings are also relief prints.

Intaglio Prints

Etchings and engravings are a typical form of Intaglio printing as an art form. The process involves transferring an image into a (usually) metal plate by using acid to etch lines and textures into its surface through a resist (etching), or cutting directly into the surface with special tools (engraving). Drypoints are prints made from images that are scraped or drawn into the plate so that a burr is raised above the surface. (Ink will catch in the burr as well as go into the scratches and this effect will give the print its characteristic smudgy look.) Inks are then rubbed into the image cut below the plate surface, and the face of the plate is wiped clean. Paper is then pressed onto the plate using considerable pressure so that it will lift the ink out of the crevices transferring the image.

Web Printing
Commercially, this process, called Gravure, is used to print some magazines and wallpaper. In this case, the printing 'plate' is usually an engraved steel cylinder that is put onto a press that will print a continuous strip (the web) of paper or vinyl (for wall coverings). Ink is rolled onto the cylinder and scraped off by a stationary steel blade leaving ink in the engraved 'cells'. The web is pressed into contact with the printing cylinder and lifts the ink from the cells. All of this happens simultaneously as the press is running. Only one color is printed at a press, so a typical set-up is a series of presses and driers that prints a succession of colors on a web in one pass, to build up a final multi-colored product.

Planography

Planography is a general term used to describe printing from a flat surface. The technique is based in chemistry, the idea that water and oil do not mix. The technique was first done on on limestone slabs and is called lithography. A slab of limestone is typically 3 to 5 inches thick and can have a printing surface up to 2 by 3 feet. Stones that artists use are typically smaller. The surface is ground smooth with water and various grades of corubundum grit. An image is drawn onto a dry stone in some sort of greasy medium; there are lithographic pencils in various grades of hardness for pencil and crayon effects and there is tusche in stick and liquid form which can be mixed with water for spattering, painting, and is also used to achieve watercolor effects. After the image is finished, it is powdered with french chalk and rosin. The stone is then etched with a mixture of acid and gum arabic, blotted, and allowed to stand overnight. With the image set, the gum is removed with water and a solvent is used to remove the greasy medium leaving a faintly visible image on the stone that will hold ink as printing takes place. An oil-based ink is then rolled onto the damp stone and it gradually builds up in the areas where the original image was drawn. The stone is fanned dry and paper is placed on it, packing and a scraper board is laid on top of the paper and the whole sandwich is run through a press equipped with a scraper bar. The scraper applys the pressure necessary to transfer the inked image to the paper.
Modern technology has developed the use of thin, light weight zinc or aluminum plates to replace the heavy and fragile stones. These light weight metal plates are attached to rotary presses for direct 'lithographic' printing. Images can be drawn on to the plates but are usually transferred photographically. Offset printing is also a form of plano( or litho-)graphy. In this type of printing the image is transferred from the metal plate to a rubber blanket (also on a roller) which then transfers the image to paper. This type of printing can be either web or sheet fed and a typical example would be a magazine or newspaper. One advantage to offset printing is that the plate is not a mirror image and can be read as easily as the print made from it.

Serigraphy

Silkscreen printing is basically a stencil method of printing. The stencil is attached to or imbeded into a fabric, usually made of synthetic fibers, stretched over a frame. The frame is attached to a table by hinges on one of its sides with the screen side closest to the table.

To print a serigraph , or silkscreen print, a loose ink is poured onto the screen inside the frame and the screen is flooded by spreading the ink with a rubber blade called a "squeegee". Light pressure is used so ink will not be forced through the screen. The frame is lifted and paper is placed under it. The frame is lowered and the squeegee is pulled across the screen with enough pressure to force ink through it onto the paper. Since one color is is printed at a time, a number of screens and stencils are needed to complete a multi-colored image.
When fabrics or wall covering is screen printed the set-up may be different. ...( to be continued. . .)