Emulsions in screen printing are exposed to blue or ultraviolet light to harden them.
The exposure is done through film carrying a positive image (like a photographic negative, but it is positive).
For indirect emulsion, in which the emulsion is a layer on a film or paper, the exposure comes first, the soft areas, where the image is, are washed away, and then the emulsion is applied to the screen, to which it adheres.
For direct emulsion, the emulsion is a liquid, which is applied to the screen and allowed to dry. It is then exposed, washed out and dried.
Indirect emulsion is better at carrying detail, but wears quickly and cannot stand flexing.
Direct emulsion produces tougher and longer lasting screens, but is not as good at carrying detail. To give an idea of what fine detail means, special techniques allow direct emulsion to carry 8 point type on a 255 mesh screen.
In screen printing - Direct emulsion is a liquid substance, that when coated onto a mesh with a scoop coater, dries to form a photosensitive film. Indirect emulsion is a sheet of dry emulsion that is typically adhered to mesh with a solvent. When either emulsion is applied mesh, and is dry, it can be exposed to light and creates a stencil of the art to be printed.
Polystyrene, polyvinyl alcohol, and polyvinyl acetate are not typically used in screen printing emulsions. Screen emulsions are usually made from light-sensitive compounds like diazo or photopolymer emulsions. These compounds provide the necessary properties for the emulsion to adhere to the screen and create a durable stencil for printing.
The standard mixing ratio of photo emulsion and sensitizer is typically 1 part sensitizer to 12 parts photo emulsion. This combination allows for proper light sensitivity and adhesion to the screen mesh for effective screen printing. It is important to mix thoroughly and follow the manufacturer's instructions for best results.
Companies use several techniques to print images on T-shirts — each with its own style, durability, and cost. 1. Screen Printing This is the most common and traditional method used by apparel printing companies. A stencil (or “screen”) is created for each color in the design. Ink is then pressed through the screen onto the fabric. It’s ideal for bulk orders and bold, vibrant designs. Pros: Long-lasting, bright colors. Cons: Not ideal for complex, multi-color photos or small batches. 2. Direct-to-Garment (DTG) Printing DTG uses a specialized inkjet printer to print the image directly onto the T-shirt. It works similarly to a home printer — but with textile inks. Perfect for photo-realistic designs, gradients, and small runs. Pros: Full-color detail, no setup needed. Cons: Works best on 100% cotton and may fade over time if not cared for properly. 3. Heat Transfer Printing This process uses heat and pressure to transfer a printed design (on special transfer paper or vinyl) onto the fabric. Commonly used for custom T-shirts and sports jerseys. Pros: Great for on-demand printing and personalization. Cons: May peel or crack after repeated washing. 4. Sublimation Printing Sublimation is used mostly on polyester or light-colored T-shirts. The design is printed on special paper with sublimation ink, then heat-pressed. The ink turns into gas and bonds with the fabric fibers. Pros: Colors are vibrant and permanent. Cons: Only works on polyester fabrics and light colors. 5. Embroidery (for Logos) While not technically printing, many companies use embroidery for logos and branding. It gives a professional, textured look that lasts longer than ink-based prints. If you want high-quality, long-lasting T-shirt screen printing in Tampa or anywhere else, look for professional "TRINITY GRAPHICS" that specialize in custom apparel, screen printing, and DTG printing services—they can help you choose the best method for your fabric and design.
In screen printing, the positive typically refers to the film or transparency that contains the design to be printed, which is usually in black. The black areas on the positive block the light during the exposure process, allowing the emulsion on the screen to remain unhardened. The resulting exposed areas will be where the ink passes through during printing. Thus, the color of the positive is predominantly black for clarity and effectiveness.
why is screen printing important
The exposure time needed for exposing emulsion with a 300-watt light will depend on factors such as the distance between the light source and the emulsion, the type of emulsion being used, and the specific requirements of the emulsion manufacturer. It is recommended to perform a test strip to determine the optimal exposure time before exposing the entire emulsion.
A screen making kit for creating custom designs on fabric or paper typically includes a screen, a squeegee, emulsion, a light source, and a design template. These components are essential for the process of screen printing, where a design is transferred onto a surface through a mesh screen.
The textile ingredients include the fabric need to be printed, the graphics for printing, the screen printing ink for printing and the printing tools. If digital textile printing, the printing tool can be only a digital textile printer. If tradition screen printing, the printing tools include screen mesh and plate, squeegee, photo emulsion etc. The screen printing inks also refers to the formulations, and printing operations and techniques, as there are so many different kinds of textile printing inks. for instant, water based ink, silicone ink, plastisol ink, heat transfer ink and digital ink etc.
Tools and materials needed for fabric printing include fabric, ink or dye, screens or stencils, a squeegee or roller for applying ink, a printing table or surface, and a heat source for setting the design. Additional items may include masking tape, emulsion, and a light source for screen exposure.
Screen print graphics are pictures or photographs that are used in the process of screen printing. Screen printing is used to do many duplications of the same design for example in t-shirt printing.
Stephen Russ has written: 'Practical screen printing' -- subject(s): Screen process printing 'Setting up in screen printing'