Screen Print Color Separation
Screen print color separations built by hand: spot color, halftones and simulated process, with a choked underbase, traps, registration marks and Pantone names, ready to output to film.
Separations your press can actually print.
A screen printer can only print one ink per screen, so every design has to be split into clean, separate layers before it goes on press. I build those separations by hand from your artwork: one layer per ink, a choked underbase for dark shirts, registration marks and Pantone names, ready to output to film.
What color separation does
Color separation turns a finished design into the set of films a screen printer needs. Each ink gets its own layer, printed as a solid black film positive. That film is used to burn a screen, and the screen prints only that one color. A three-color logo on a white shirt needs three screens; the same logo on a black shirt usually needs four, because a white underbase goes down first so the colors stay bright on dark fabric.
Good separations save you money on press: fewer screens, fewer test prints, less ink and less time spent fixing registration. Bad ones show up as white halos, gaps between colors, lost fine lines and muddy shading, and every one of those problems starts in the file, not at the press.
The diagram shows the idea on a simple concept badge: the printed result on a navy shirt, then the three films behind it. The underbase is slightly smaller than the colors so it never peeks out, the yellow has the star knocked out so the red prints on the underbase rather than on top of yellow, and the red is given a small trap so no navy shirt shows between the two inks.
Separation types I build
The right method depends on the artwork, the garment color and how many screens your press holds. If you're not sure, send the design and I'll recommend one.
| Separation type | Best for | How it prints |
|---|---|---|
| Spot color | Logos, text, team and event shirts with flat colors | One solid screen per ink, matched to Pantone. Cleanest and cheapest to print |
| Spot color + halftones | Shading, gradients and soft shadows with a few inks | Halftone dots build lighter tints from the same spot inks, so you get more tones without more screens |
| Simulated process | Photos, detailed illustrations and realistic art on dark garments | Plastisol spot inks plus an underbase and highlight white blend into a full-color look, usually 6 to 10 screens |
| Index | Bold, high-contrast art and retro posters | Square, same-size dots in solid inks. Easy to register and very consistent from shirt to shirt |
| Four-color process (CMYK) | Photo prints on white or light garments | Cyan, magenta, yellow and black halftones. Needs fine mesh and tight registration |
What's set up on every separated file
- One named layer per ink, set as a spot color with its Pantone name, so your RIP or output software prints the right films
- White underbase for dark and colored garments, choked inward, plus a highlight white when the design needs it
- Knockouts so inks don't stack and turn muddy, and overprints only where you want them
- Traps where colors meet, sized for a normal manual or automatic press
- Registration marks on every film, in the same place on every screen
- Minimum line weights so fine lines and small text hold on the mesh
- Halftone settings (dot shape, line count and angle) when tints or shading are used, matched to your mesh if you tell me what you run
- Print size set to the actual print area, for example a left chest, full front or sleeve
Dark garments and the underbase
Plastisol and water-based inks are partly transparent, so a yellow printed straight onto a navy shirt looks dull green. The fix is a white underbase printed and flashed first, with the colors printed on top. The underbase is choked a little smaller than the colors, and in shading areas it's reduced to halftones so the print stays soft instead of feeling like a thick plastic patch. For simulated process, a final highlight white brings back the brightest points of the design.
Tell me the garment color when you order. A design separated for a white tee and the same design for a black hoodie are not the same set of films.
Common separation problems and the fix
If your prints keep coming out wrong, the cause is usually in the separation. These are the problems I fix most often in files that other people or auto-separation tools made.
| Problem on press | Usual cause in the art | Fix in the separation |
|---|---|---|
| White halo around colors | Underbase the same size as the colors | Choke the underbase so it sits just inside each color |
| Gaps where colors meet | No trap, so slight misregistration shows the shirt | Add a small trap where one ink overlaps the next |
| Fine lines or text missing | Lines thinner than the screen can hold | Set a minimum line weight and thicken thin details |
| Muddy, dark colors | Inks printed on top of each other without a knockout | Knock out each color from the ones below unless an overprint is intended |
| Moiré or blotchy shading | Halftone angle or line count wrong for the mesh | Set dot shape, line count and angle for your mesh and press |
| Too many screens | Every shade treated as its own color | Merge similar colors and use halftones for tints |
Starting from a blurry JPG, PNG or a photo of a shirt
Most artwork that arrives for screen printing is a small JPG, a screenshot or a photo of an old print. Separating that file directly gives soft, jagged edges on every screen. So the design is first redrawn by hand as a clean vector, with smooth curves and crisp text, and then separated. You get both: the vector master for future jobs and the separations for this one. The same vector can later be used for DTF, vinyl, signs or turned into an embroidery file.
What to send
- The artwork: AI, EPS, PDF or SVG if you have it, otherwise the best JPG or PNG you can find
- The garment color, or several if the design prints on different shirts
- The print size and placement: left chest, full front, back, sleeve
- The ink colors or Pantone numbers, if the brand has them
- How many screens your press holds, and your mesh count if you use halftones
- Ink type if it matters: plastisol, water-based or discharge
What you get
Vector separations as AI, EPS and PDF with each ink on its own named spot color layer, a separated PDF with one page per screen and registration marks, a composite preview on the garment color and a color list with Pantone names in print order. Simulated process and halftone jobs can also come as a layered PSD with one channel per ink. Small edits after your first print are free until it's right.
Price
Spot color separations on a simple logo start at $8, the same starting price as vector conversion. Artwork that needs a full redraw, halftones or simulated process is quoted as a fixed price upfront, based on the number of colors and the level of detail, usually within the hour. Printing for customers every week? The print shop partner page explains how regular orders work.
Frequently asked questions
What is color separation in screen printing?
Color separation splits a design into one layer per ink. Each layer is printed as a black film positive, burned onto its own screen and printed in its own color. A three-color logo on a dark shirt usually needs four screens: a white underbase plus one screen for each color.
Which separation type do I need?
Spot color is best for logos and text with flat colors. Spot color with halftones adds shading and gradients with the same inks. Simulated process is used for photos and detailed illustrations on dark garments, and index separation uses square dots for a bold, high-contrast look. Send the artwork, the garment color and how many screens your press holds, and I will recommend one.
Can you separate a low-resolution JPG or PNG?
Yes. A blurry or small image is first redrawn by hand as a clean vector, then separated. Separating a pixelated file directly gives rough edges on every screen, so the redraw is what makes the print sharp.
Do you add a white underbase for dark shirts?
Yes. For dark garments I build a white underbase, choke it slightly so it does not peek out around the colors, and add a highlight white when the design needs it. Tell me the shirt color so the underbase is set up for it.
What files will I get?
Vector separations come as AI, EPS and PDF with each ink on its own named spot color layer, plus a separated PDF with one page per screen and registration marks. Simulated process and halftone jobs can also include a layered PSD with one channel per ink. You also get a color list with Pantone names and a composite preview.
How much does color separation cost?
Spot color separations on a simple logo start at $8. Artwork that needs a full redraw, halftones or simulated process is quoted as a fixed price upfront, based on the number of colors and the detail. You see the price before any work starts.
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