Why screen printers want vector art
Screen printing pushes ink through a mesh stencil, one screen per color. Each screen is made from a separation — a positive holding just one ink’s parts of the design. Vector art makes separations easy: every shape of one ink has exactly the same fill, edges stay crisp at any print size, and nothing is soft or in between. A blurry PNG gives soft edges, and soft edges make ragged stencils.
Decide the number of inks first
Every ink is another screen, another setup, and another cost, so most spot-color jobs use one to four inks. Decide how many the job can carry — and which colors — before you trace. A design traced into seventeen colors can’t be printed as spot colors until it has been reduced, so it’s easiest to reduce it at the source.
Build the palette around your inks
- Upload the design, then open Settings → Palette → Choose palette.
- Slide Simplify Colors down to your ink count plus the background.
- Merge any near-duplicate shades by dragging one swatch onto another. Screen printing can’t reproduce the soft blends along the edges anyway.
- Click each swatch and set it to the ink you’ll print. A hex value is a screen approximation, so give the printer the real ink reference — a Pantone number, for example — alongside the file.
- Apply changes, then apply again in the settings to re-trace.
Don’t print the shirt
The garment is a color you don’t print. If the design sits on a background that matches the shirt, hide that swatch — or switch on Remove background — so it doesn’t turn into an extra screen printed in the shirt’s own color.
On dark garments, light inks are usually printed over a white underbase. That’s the printer’s part of the job: send the design’s colors, and let them build the underbase.
Keep the details printable
- Tiny specks and hairlines may not hold in the mesh, or may fill in. Raise Minimum area (Advanced → Small regions) to clear specks, and check thin strokes at the actual print size.
- Keep flat fills. Spot-color screen printing makes gradients with halftone dots, which the printer handles. Use the Filled draw style, not Gradients.
- Photos can be posterized into a few flat colors for a graphic look — see turning a photo into vector art — or printed as halftones, which is a conversation to have with your printer.
Knockouts and overprints
Where two inks meet, a printer can knock out — the lower color has a hole where the upper one prints, so the inks sit side by side — or overprint, printing one ink on top of the other. Knockouts keep colors true but show a gap if the screens shift slightly, so printers usually add a small overlap called a trap.
- The General use preset gives you knockouts: each shape is set into a hole in the shape beneath it. This is what most printers expect.
- The Easy editing preset stacks shapes instead: lower shapes stay whole, with smaller shapes on top — the overprint layout.
Set the print size
Under Advanced → Output size, choose Custom and type the print width in inches or centimetres — a typical adult front print is around 10 to 12 inches wide. Leave the height empty to keep the proportions. Because the file is vector, the printer can still resize it without any loss.
What to send the printer
- PDF or EPS — what most print shops ask for. Every shape of one ink shares the exact same fill, so in Illustrator, Select → Same → Fill Color picks up a whole separation in one click.
- SVG with the Easy editing preset if the printer works that way — shapes arrive grouped by color, one group per ink.
- The ink list: each color’s ink reference, the print size and position, and the garment color.
- A PNG mockup for approval — set Output size to Scale at 2× or 4× for a crisp preview.
The vector format guide explains the differences between PDF, EPS, and SVG in more detail.