Intaglio printmaking encompasses etching, engraving (including photo etching / engraving). The print itself is produced from a plate with grooves, lines, or textured fields. When coated with ink and wiped clean, these marks hold ink.
Then, dampened paper is laid over the plate and pressed together. The softened, damp paper picks up the ink, producing the image.
Lithographic printing operates under the premise "oil and water don't mix." An image is applied to either a fine-grained, milled piece of limestone, or a milled sheet of aluminum (plate). The image can be applied by hand or using a photographic process.
After image application and processing (which differs for each type of surface), the negative, non-printing area of the plate is hydroscopic (accepting of water), while the positive image area is hydrophobic (resistant to water). Oil-based ink is rolled onto the plate/stone. The ink sticks to the positive areas but is repelled by the wet, non-printing areas. A dry sheet of paper is laid over the inked plate and pressure is applied across the surface. The image on the plate is a reverse of the printed sheet.
Letterpress printing is a form of relief printing. Traditionally, it involved hand-setting movable type: a series of individual letters, numbers, or figures, arranged and aligned to produce the desired text. Modern techniques have incorporated digitally produced layouts. In this case, pages of text can be printed to film, and then exposed to a photosensitive polymer plate.
After processing, the text forms a raised surface on the plate. With either polymer plates or moveable type, printing is done on a press which inks and prints in a single, automated motion. Paper is hand-fed and the inked text is debossed into the surface of the paper.
Screenprinting is a modern printmaking technique. A sheet of fine-mesh silk, or more commonly, nylon mesh, is stretched over a frame of metal or wood forming a screen. A photosensitive emulsion is applied to the screen, and an image is exposed into the emulsion. After processing, the exposed emulsion reveals the shape of the image: the image is open mesh, while negative, non-printing space is sealed.
The frame is locked into a set of hinged clamps. Using a rubber-bladed squeegee, ink is pressed through the screen to the paper producing an image. Different thread-count meshes can be used to produce more saturated or finely-detailed images.