Screen printing is a cost effective way to easily manufacture many products, such as shirts and signs. The relatively large nature of a screen press allows many larger products to be made quickly, and with a variety of inks. There are five major types of screen ink: solvent, water, plastisol, soy-based and UV curable.
Solvent
Found in many ink jet printers, solvent inks are inexpensive. These inks can be applied to outdoor signs or products due to their ability to stick to non-absorbent materials such as metal, powder-coat, porcelain and enamels. Pigment, carrier fluid and resin are the main components of solvent inks. While the ink's color is determined by its pigment, hardness is derived by the resin after drying, and its viscosity is set by the carrier fluid.
Water
Typically used with paper and fabric products due to their absorbent nature, these environmentally friendly inks utilize pigments in suspension with water acting as the solvent. This ink is cured as its water solvent evaporates, leaving the pigment behind. Room temperatures can cure the ink, but the process can be quickened with a heated dryer.
Plastisol
These inks feature a polyvinyl chloride (PVC) system that typically contains no solvent. Known as a 100 percent ink system, these inks are a thermoplastic which requires heat to cure. This heat crosses the PVC resin molecules with an included plasticizer, hardening the ink on the product. Plastisol inks are commonly used for printing T-shirts, patches, jackets and other hard worn fabric products. Plastisol ink formulas vary, including the options of adding solvent or water bases for custom finishes.
UV Curable
Like plastisol, these inks are a 100 percent ink system with no solvent to be evaporated for curing. They lack volatile organic compounds (VOCs) which can harm the environment as well as the user. Such inks are cured very quickly with a powerful ultra-violet light, providing a quick product turnaround. UV inks do not dry to the screen itself, and can have excellent color transparency. However, they do require expensive equipment to use and therefore, add to the production costs.
Soy-based
In response to the potentially harmful phthalates found in PVC products such as traditional plastisol inks, soy-based plastisol screen inks have been engineered as a healthy alternative. These inks require the same printing and curing processes as its PVC relative, but feature excellent stretchability and require either a cotton or nylon fabric base.
