How to Make an Exposure Unit for Emulsion in Screen Printing
You can make an exposure unit for use with photo emulsion in screen printing. The emulsion and screen printing frame must be sourced from an art supply store or screen printing supplier, but everything else you need to construct this exposure unit is available at a hardware store. Professional exposure units are available but are expensive; prices begin at over $1000. This exposure unit can achieve professional results at a fraction of the cost.
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Things You'll Need
- Screen printing frame with mesh
- 4-inch thick foam rubber
- Scissors
- Photography darkroom with running water
- Photo emulsion
- Squeegee
- Film positive
- Glass 1/4 inch thick
- Halide light
- Newsprint
Instructions
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Measure the inside dimension of a screen printing frame. Cut a piece of foam rubber to fit snug inside the frame.
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Clean the mesh on the screen printing frame with soap and water and let it dry overnight. In a photography darkroom, coat both sides of the screen printing frame with photo emulsion with a squeegee or stiff piece of art board. Scrape off any excess drippy emulsion. Set the screen face down in a dark place to dry.
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Create a film positive of the design you want to put on the silk screen frame. Print your design on a piece of clear vellum paper. This is called a film positive.
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In a darkroom, place the foam rubber face down on a flat surface. Place the screen face down over it, fitting the foam rubber inside the screen. Put the film positive face down centered on top of the screen. Place the glass over the film positive. The glass should be big enough to cover the silk screen frame.
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Hang a halide light 18 inches over the glass. Turn the light on to expose the screen to the design. Turn off the light after eight minutes. Rinse both sides of the silk screen frame with warm water under medium pressure until the design appears. Blot both sides of the exposed image with newsprint to remove excess emulsion.
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Place the screen in the sun or a well-lit area to dry. Once dry, the screen may be used for screen printing, also known as silk screening.
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Tips & Warnings
Add sensitizer to the photo emulsion before coating the silk screen frame with it. The sensitizer comes with the emulsion and must be mixed into it to activate the emulsion.
Increase your exposure time if the emulsion washes out. Decrease your exposure time if the emulsion sticks in the screen.
Your film positive must be opaque to successfully expose a screen. Hold the film positive up to the light to check opacity. If it is not opaque enough, brush black ink onto on the back of the image.
