Screenprinting is a type of direct transfer printing, where the fabric is covered with a screen-like mesh, usually made from vinyl or some other semi-rigid plastic. The mesh is placed over a stencil and the fabric is loaded into the printer. Once the desired image is printed, the mesh is removed and the final image revealed. Screen printing has several advantages over other common printing methods; the most obvious being that it uses very little ink and is perfect for printing items that don’t require drying time, and for areas that don’t suffer from damage.
The substance used is rolled onto the mesh in either a spray or roll-to-roll method, and either the stencil, which is generally made of strong metal foil, or an antifouling material, such as xylene or ethylene propylene diene monomer, are applied to the image. The image then cures in a process similar to dye sublimation. The image passes through a special nozzle on the printer head that forms a semi-permeable membrane that blocks some of the chemicals from the rest of the ink and only allows the tiny droplets of ink to pass through. Because the ink used in screen printing is typically thicker than that used for dye sublimation, it requires a lower cost per unit of print, making emulsion printing practical for use in small quantities.
Unlike dye sublimation, in which a stencil must be used to create an image, emulsion printing requires no stencils or other specialized equipment. The image is created on the surface of the mesh just as with dye sublimation, and then is passed through the printer head in the same fashion as other forms of screenprinting. One difference is that there are no heat cycles used in the process, so the screen must be hot enough to pass through the mesh. Another difference is that it is important to make sure that all of the screen that is used in emulsion printing has been cured, or else the finished product will not come out the way that was intended.
There are several different types of emulsion based screens that can be used for screen printing. These include solid emulsion printers that produce a single color, milky, translucent image, and matte, opaque images like the type found in court exhibits and legal briefs. There are also gloss, semi-gloss, and high gloss screens that produce colors in various rainbow shades.
There are several different ways how the screen is applied to a substrate. In a solid screen printer, the substrate is coated with ink before being passed through the screen. This coating provides the solid image to be printed on. The mesh, also called a stencil, is affixed to the substrate and holds the image in place. Before any printing happens, the stencil is erased and a fresh mesh is placed over the stencil to be printed on. Screenprinting a solid substrate produces a hard, durable material that can be used for years.
A semi-gloss emulsion printer sprays a liquid emulsion onto the substrate. A dye is usually added to this mixture to produce different colors. The emulsion is peeled off the next day and a new mesh is applied to produce the final design. Screen printing with a semi-gloss substrate produces a semi-translucent finish that looks like glossy paper or glass. High gloss emulsion printer sprays a dye over the emulsion, which is peeled off and replaced by another sheet of emulsion. This is used in conjunction with a squeegee to create a nozzle that produces high quality images with vibrant, brilliant colors.