How Does Photo Emulsion Work?
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History
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The earliest known uses of silk screen printing were developed on the continent of Asia, and were not much different than the methods that are used by today's artists. The most commonly used style of silk screening, which involves the use of stencils, has stood the test of time, and has further evolved into a high tech industry. Most importantly, over the past seventy five years, silk screen printing has come to depend on the use of a photo emulsifier to burn a desired image into the mesh frame.
What is it?
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Photo emulsion is a liquid that is sensitive to the sun's rays, or other producers of ultra violet light. Once the photo emulsion comes in contact with air, a chemical change occurs that transforms it into a hardened substance. Most photo emulsions are thick in consistency, and resemble that of morning pancake syrup, and must be refrigerated. The active chemical is generally a PVA suspension, otherwise known as bichromated polyvinyl alcohol. The shelf life of photo emulsion varies by manufacturer, but is generally viable for up to one month.
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How it Works
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The photo emulsion technique of silk screen printing, relies heavily on the artist's ability to multi task, and incorporates a combination of precision and craftsmanship in order to work as it should. The artist must create a stencil of his design on clear acetate, and all of the areas that are expected to be inked must be filled with a dark, opaque color. Next, the photo emulsion is spread over a piece of fabric mesh that has been framed with wood, just like a window screen. Finally, the acetate stencil is placed over the photo emulsified mesh, and a chemical process will take place, burning the acetate image into the mesh. The screen is then washed with a solution that removes the remainder of the photo emulsion product, rendering the screen ready for the inking process.
Let the Sun do the Work
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Although the silk screening process needs to adhere to a strict set of rules that, if followed correctly, produce a fantastic result, that does not have to involve a big budget. Contrary to popular belief, an artist does not need a lot of fancy, high-tech equipment to do small-scale work. Any mesh like fabric, pulled evenly and tightly over a wooden photo frame, will work just like a professional-grade screen. Just be sure to remove the glass. The emulsion can then be spread with the cardboard pieces that were inside the wood frame, and left to dry. The sun can then be used in place of ultraviolet light bulbs, for the burning effect. By placing the screen on a piece of black fabric, face down, and then laying your stencil over it, along with a clear piece of glass on top of the stencil, the sun will work to burn the image onto the screen. Once the image has successfully transferred, rinse the screen with water to remove the photo emulsion, and allow the screen to dry. It is now ready for inking.
Safety
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Keep in mind that photo emulsion is a chemical that is capable of burning the eyes and skin. Proper safety gear such as rubber gloves and goggles should be worn during its application. Photo emulsion should also be used in a well-ventilated area due to the harmful vapors that it emits, and should be kept out of the reach of children and pets. The chemical also has the potential to be life-threatening if ingested, and will require immediate medical attention.
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Resources
- Photo Credit Jonae Fredericks
