Reaping the benefits of digital imaging on apparel requires command of art preparation. This article describes how to set up garment graphics for inkjet printing and examines the variables associated with this method of decoration.
Several of the DTG inkjet printers out there have the capability to print white ink. Making the most of this new feature requires that you test the process to see what the results are with a variety of opacities and line weights with overprinted colors. A simple grid, similar to the one that is used to test color shift in screen printing, works well here too (Figure 3). Just remember that the colored inks on an inkjet printer have little or no ability to stand out without the white underbase on a dark garment. Furthermore, ink-film thickness is much thinner than a screen print. A good way to use this file is to run a test print on a shirt, printing bright reds, blues, greens, oranges, yellows, pinks, and assorted rich hues in strips up and down the shirt. This should give you a picture of what you’ll get when you have less than a solid underbase.
The artwork function that needs to take place to generate the underbase is one of the areas many printers overlook. The steps you’ll need to take vary significantly, depending on the DTG printer you have. The common method for preparing a white underbase for a digital file is to turn all areas black that would show through onto the shirt and then convert this copy of the artwork into L*a*b* color mode. The next step is to copy the lightness channel and invert it for a working underbase. This is a passable method when the white underbase is heavy enough, but it may still be too imprecise for other reasons. The brightest reds and deepest blues in an RGB file will register as a 50-60% gray in the L*a*b* lightness channel, yet to reproduce even close to these hues on a final DTG-printed piece, the underbase will need to be the brightest white possible.
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