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Screen Printing Goes Boom

(April 2011) posted on Tue Apr 12, 2011

This article demonstrates the importance of broadening your skill sets and experimenting with new materials and techniques.

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By Ryan Moor

It was almost midnight on Sunday when I discovered that this project was anything but simple. I saw the reasoning behind why so many printers had turned Tyler’s last-minute request down; screen printing on glass is not at all like screen printing on T-shirts (Figure 2). The ink I used had to be printed through 25 x 36-in. screens (230-thread/in. mesh) coated with a special, solvent-resistant emulsion. The glass had to be cleaned on both sides, registered, and stacked to air-dry for at least 12 hours. The real fun began after the screens were prepped, coated, and dried; the films were printed; stencils exposed; screens taped; off-contact set; and print registered. The gloss-enamel formulation I used is an air-curing ink and, by its apparent properties, this ink dries rather quickly in the screen. Combine that with a glassy surface and you’ve got yourself a completely different animal than a T-shirt.

In the middle of the project
After two hours into printing this project without any success—and with two bottles of screen opener used up—things finally started working. This is what I learned about screen printing on glass: Glass is slippery—especially after it’s cleaned. The ink I used is thick, and glass doesn’t receive ink all that well in the first place. When printing on glass, cleaning it first and then letting each piece dry and warm up before you attempt to print on it is crucial. Proper off-contact is also critical when printing on a slippery, rigid substrate. Because I was printing with large-format static frames, known for lower screen tension, I had to double my off-contact to almost 0.25 in.

I have always been told to thin enamel ink down to 2-3%. While this modification may work well for printing on metal or wood, it did not work well for glass. Most of the troubleshooting during the first few hours of testing focused around the consistency of the ink. If the ink is too thin, it will leave extremely messy and unacceptable edges. The text I printed was bold and linear, so it absolutely needed to be clean and precise. In the end, the key to the proper consistency was using the ink straight out of the can. This gave the most even and highest quality print possible, which was the formula I used repeatedly until the job was completed.


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