Emulsion is the light-sensitive coating applied to a prepared mesh screen to create the stencil – the heart of the screen printing process. When the coated screen is exposed to UV light through a film positive or digital output, the emulsion hardens in the exposed areas and remains water-soluble in the unexposed (image) areas. Washing the screen removes the unexposed emulsion, leaving open channels through which ink will pass during printing. Choosing the right emulsion type is essential, as it affects exposure speed, stencil durability, ink compatibility and print resolution.
Computer-to-Screen (CTS) Emulsion
Computer-to-Screen (CTS) emulsion is specially formulated for use with direct digital imaging systems that expose the screen using laser, LED, or inkjet light sources – eliminating the need for a physical film positive. CTS emulsions are engineered to be highly sensitive to the specific wavelengths used by CTS units (typically UV-LED), enabling very fast and accurate exposure. They deliver exceptional edge definition, sharp stencil walls and outstanding resolution for fine detail work. CTS technology is rapidly gaining adoption in modern print shops for its speed, repeatability and the elimination of film costs and chemical processing. These emulsions are available in both SBQ photopolymer and dual-cure variants and are compatible with a wide range of ink systems.
Pre-Sensitized SBQ Emulsion
SBQ (Stilbene-based Quaternary) emulsion, also called pure photopolymer emulsion, is a single-component, ready-to-use product that requires no mixing prior to coating. The photosensitive molecules are pre-bonded to the polymer solids and cross-link rapidly when exposed to UV light, making SBQ emulsions significantly faster to expose than diazo-based alternatives — typically 8 to 10 times quicker. They offer excellent bridging properties, fine detail reproduction and a long shelf life. SBQ emulsions are the preferred choice for high-volume production environments and for use with plastisol inks. They are well suited to LED and CTS exposure systems and are particularly valued by printers requiring consistent, repeatable results with minimal setup time.
Water-Resistant Emulsion
Water-resistant emulsion is formulated to withstand prolonged contact with water-based inks, discharge inks and reactive dyes-ink systems that can degrade standard stencils over long print runs. Available in both pre-sensitized (SBQ) and dual-cure versions, water-resistant emulsions undergo additional chemical cross-linking after exposure, often aided by a post-exposure hardening treatment, to create a highly durable and ink-resistant stencil. This type of emulsion is essential for water-based ink printing on textiles, where stencil breakdown due to ink moisture is a common challenge. The result is a stencil capable of tens of thousands of impressions without degradation, making it a cost-effective choice for long runs.
Diazo Emulsion
Diazo emulsion is a two-part system consisting of an emulsion base and a separate diazo sensitizer that must be dissolved and mixed before use. Once sensitized, the emulsion has a working shelf life of four to six weeks when stored away from light and heat. Diazo emulsions offer a wider exposure latitude, giving operators more flexibility in exposure timing – an advantage for shops without precise exposure units. They are notably more water-resistant than standard pre-sensitized emulsions and produce strong, durable stencils for use with water-based inks. Cost-effective and reliable, diazo emulsions remain widely used in small to medium-sized print shops, particularly for garment printing, advertising banners, and applications where large, solid areas of colour are the norm rather than fine halftone detail. They are best suited to conventional UV exposure units and lower mesh counts (35-90T).
