Striking a balance between vibrant colors and subtle details requires a careful approach to creating separations. Trimingham describes his favorite method in this month's column.
Will a color other than white work as an underbase? With dark shirts, white isn’t always right—especially when the overall image has a color cast (as in an old west photo or one of those night shots with an infrared camera). In cases like these, the use of an opaque color instead of white as an underbase can be very effective. A large run with a bigger investment would benefit from a test run to see how this option would make top colors shift in hue. I have used cream, gray, and cool or warm gray as underbase alternatives. One Halloween shirt came out amazingly well using a lavender underbase for the spooky trees and haunted house.
Will this design only go on black? If the separation set needs to work on other garment colors then, you’ll need to use a very opaque underbase. White is typically the best choice. You’ll have to make additional allowance for the separations to work in a black separation if needed.
If I use a gray underbase, will the design work with a highlight white or will a composite underbase be needed? Some designs just need a little more care than others. An image that has an extreme value range with a lot of highlights and an equal amount of shadowy details benefits from a gray-flash-white-flash underbase sequence to create an underbase with a complete value range that can provide a more significant gamma boost to hot colors and not kill all of the shadows. The downside of this scenario is the tendency for this to push the print into three flashes on press. A lot of printers won’t consider a job with three flashes unless it’s a manual job or a small revolver run on a press that can cycle around.
Can I reduce the top colors slightly to minimize tack without killing opacity? One of the biggest issues with printing a lot of colors on black shirts is that the inks for the top colors pick up on the backs of the screens, which leads to dot-gain shift after several dozen shirts. A great way to avoid this is to add some dulling agents and viscosity reducers to the inks to make them less sticky. The key is to keep the maximum brightness and opacity while slightly adjusting the inks to help them stabilize on press so that more flashes aren’t needed.
Take time to test
Greater detail in the shadows of your prints is available if you take the time to test your ink set and see where the fall-off point is with your inks. Using this tool as a guide can help to reduce colors in designs, create more drama on dark shirts, and give artists some clearly defined variables to create the best separations possible. The result will be prints that really knock customers over and boost your dark-garment sales.
Thomas Trimingham has worked in the screen-printing industry for more than 15 years as an artist, art director, industry consultant, and head of R&D for some of the nation's largest screen printers. He is an award-winning illustrator, designer, and author of more than 45 articles on graphics for screen printing. Trimigham can be reached through is Website, www.art2screen.com.
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