How to Expose a Silk Screen

A silk screened T-shirt

Expose a silk screen with an image for the purpose of printing it on paper, fabric, metal, plastic or wood. Your image can be a drawing, graphic design or photograph. With a trip to an art supply store and the hardware store, the materials for silk screen making are easily gathered. Once you expose a silk screen, you can make multiple prints from it. Generally, you need one silk screen for each color in your design. Try a one-color design for your first project.

Things You'll Need

• Image
• Computer
• Scanner (optional)
• Printer
• Transparent vellum
• Photo emulsion
• Screen coating tool or pressed board
• Silk screen frame
• Halide light
• Glass (1/4 inch)
• Foam rubber
• Newsprint

Instructions

1. Purchase photo emulsion and a silk screen frame from an art supply or screen printing supply store. The frame should have synthetic silk mesh already stretched across it. Wash the silk screen with a bit of detergent, rinse completely and let it dry.

2. In a dark area, mix sensitizer into the photo emulsion, stirring thoroughly. Most emulsions come with sensitizer. Coat the silk screen with emulsion on both sides using the edge of a piece of pressed board or a screen coating tool. Wipe excess emulsion off both sides of the screen. Set the screen to dry in a dark place.

3. Prepare an image. It could be a drawing, design or photo. Scan the image into your computer if it does not already exist as a file. Load your printer with transparent vellum paper. Open the image on your computer and print. The image on vellum is called a film positive. Check the film positive for opacity. If it is not opaque, turn it over and go over the image with marker or black ink.

4. Cut a piece of foam rubber to fit inside the silk screen frame. Lay it on the floor and put the silk screen over it face down. Place the film positive centered face down on top and tape into place with transparent tape. Put the piece of 1/4 inch thick glass over the assembly.

5. Hang a halide light 16 to 18 inches over the glass and turn it on. Check your emulsion instructions for exposure time, usually five to ten minutes. Turn off the light. Develop the image with a spray of warm water to both sides of the screen. Blot both sides with newsprint when done and set silk screen aside to dry. Once dry, the silk screen may be used for printing with screen printing ink and a squeegee.

Tips & Warnings

• To expose a photographic image on a silk screen, convert the image to grayscale. Use an image editing program like Photoshop to print a film positive of the image at a screen frequency of 55 line per inch. In Photoshop, use the print dialog box to navigate to screen frequency. Print the film positive with a laser printer, as some ink jet printers do not print a proper screen dot for exposing a silk screen. Use a finer mesh silk screen such as 230 mesh count for photos.

• If you image clogs and will not develop, or if too much emulsion sprays out at developing, adjust your exposure time. Try less time with a clogged image, and more time with a sprayed out image. Also check your contact between the film positive and the screen to make sure no light can get in.

References

• Reuels: Photographic Emulsion Method

Resources

• Reuels: Diazo Photo Emulsion Kit
• Silkscreeningsupplies: Screen Printing Emulsion