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Case study: from four screens on light to three on black

PrintSeps guides · updated October 2026

A customer sent us a family-reunion shirt design: a weathered pickup truck in grays and black with rust-orange accents, big orange lettering with black outlines, and a script line underneath. They asked for a light shirt. Two days later the plan changed to a black tee, and they wanted it in three colors. Here is how both separations were built and what changed between them.

Version 1: four spot colors on a light shirt

On a light garment this design is a classic spot job. The shirt is the white; black ink carries the line work; the truck's weathering is tone, so it became two gray plates (a charcoal and a dark gray) as 55 LPI halftones; the orange is one solid plate. Four screens: black, dark gray, charcoal, orange, printed light to dark in the usual way.

The only real decision was how to pick the grays. An automatic separation that chooses inks by color-space spread kept electing an unrepresentative pure red for the rust; picking inks by how much of the image they cover, then merging the near-duplicate blacks, gave the four plates above. For a spot job on a light shirt, dominant colors beat extreme colors.

What the customer asked for on black

Their request, in their words: gray, solid orange, white highlights, and a choked underlay for the text on the same screen as the highlights. And a question: can it be done without printing black on a black tee?

Yes, and that's the whole trick. On a black shirt the shirt is the black. Every black outline, every shadow in the truck, every dark gap between letters is simply unprinted garment. That removes a screen and a registration headache at once.

Version 2: three screens on black

One white screen doing two jobs

The underbase only needs to live under the orange, and the highlights only need to live where the art is nearly white. Those areas never overlap, so both fit on one film. The base part is choked by about 1 point so it can't peek past the orange; the highlight part is left at its true edge. Because the white prints first, the gray plate is knocked out wherever a highlight sits, so gray never prints over the white.

The gray plate as a tone map

With no black ink, the gray halftone is what makes the truck read. The coverage follows the brightness of the art up to the ink's own value (a medium-light gray, around 67% brightness): a pixel that dark prints as solid gray; darker pixels print as fewer dots with shirt showing between them; brighter pixels hand off to the white highlight. The same rule knocks gray out of the orange areas and out of any saturated pixel too dark to make the orange plate, which is how the antialiased edges around the lettering stay clean instead of printing as a ghost outline of gray dots.

Where to put the base

The customer asked for base under the text. We put it under all the orange, including the rust on the truck, so the orange matches everywhere, and said so in the delivery email with an offer to change it. Orange over bare black shirt prints noticeably duller than orange over white; if the rust accents are meant to look weathered, no base under them is a legitimate choice, but it should be a choice.

What the two versions share

Same art, same 11-inch print width, same 55 LPI at 22.5°. Everything else (ink count, which plate carries detail, where the whites go) came from the garment color. A separation is never just a property of the artwork; it's a property of the artwork on a specific shirt.

Takeaways

• On black, treat the shirt as an ink. Most designs with black line work lose a screen for free.
• Base and highlight can share a screen when their areas don't overlap. Choke the base part only.
• Knock the gray out around the spot color, or the lettering edges will print as a dotted halo.
• Say where you put the underbase. The customer may want the rust dull on purpose.