Screen print color separation, free

A color separation splits a design into one film for every ink. Each screen is burned from its film: where the film is black, light is blocked, the emulsion stays soft and washes out, and that ink can pass through the mesh. A design in four inks needs four films and four screens, printed one over another, plus a white underbase first on a dark shirt.

It reads the colors in your picture, joins colors that are almost the same, and treats the soft pixels along an edge as part of that edge, so an anti-aliased logo does not turn into dozens of colors. A smooth fade is kept as tones of the inks at its two ends (a halftone), not as five extra screens. You can set the number of inks, merge two, drop one, change a color or the print order. If the picture is a JPG, noise around the edges can add a color or two: merge them into the ink they belong to.

Usually only on a dark or colored shirt. Ink is slightly see-through, so a light or bright color printed straight onto black looks dull. A white film printed first, under the colors, keeps them bright. The tool draws that film from the shape of your inks and pulls it in (a choke, 0.25 mm to start) so a little misregistration does not leave a white rim. It can also print the design's own white again last, as a highlight white on top. On a light shirt you do not need an underbase, and a dark ink that looks fine straight on the shirt can skip it (an option on that ink).

Where two inks meet, a hair of misregistration shows a gap of bare shirt. A trap prevents it by letting the lighter ink print a little under the darker one next to it, where the darker ink covers it. The tool starts at 0.2 mm, which is a rule of thumb for an automatic press; a hand-pulled press often needs 0.4 to 0.8 mm. Print a test and change the width to suit your press.

Only the inks that carry a fade or shading are screened; flat color stays solid. 35 lines per inch is a common start on shirts, and a rough rule is the mesh count divided by 4 to 5 (so a 156 mesh suits about 35 lpi). Each halftoned film gets its own angle, 30 degrees apart starting from the one you choose, so the dot patterns do not clash. Dot gain is how much a 50% dot grows on press: the dots are drawn smaller to allow for it, with 15% as a starting point. All of these are starting values, not a standard: ask your printer, and print a test patch.

Print each film at 100% ("actual size", never "fit to page") on film positive or transparency, as dark as your printer goes, or take the files to a print shop. Each PNG is 1-bit black on clear with its resolution stored in the file, so it opens at its real size; the PDF has one film per page at real size with the marks and labels drawn as vectors. Hold a printed film to the light: if light shows through the black, print two and stack them.

The registration marks sit 8 mm outside the art on all four sides, at the same place on every film, so the distance between the top and bottom marks is the art's height plus 16 mm (the width plus 16 mm for left and right). Measure that on your first print before you expose anything, then stack the films on a light table and check the marks line up. If you have separated artwork elsewhere and only need the marks, the registration film tool makes just those.

Not into full color. A photo is reduced to a few inks as halftones, which gives a posterized, screen-printed look, and the tool says so when it sees one. Full-color photo printing needs simulated-process or CMYK separations with more screens than eight spot inks give, and this tool does not make those. For a one-color halftone of a photo, use the halftone generator.

No. The inks are the colors in your picture, shown with plain names and hex values, because matching a real ink needs a color library this site does not have. Mix or choose your inks to suit, and treat the hex only as a guide to what each film is for.

It reads PNG, JPG and WEBP, not vector or layered files: export a vector logo at its print size or larger first. It does not calibrate to a press, simulate how ink lies on fabric (the proof is flat colors), match ink colors, or separate a photo into full color.

The longer side of the art goes up to 24 in. A film is limited to about 60 million pixels (24 million on an iPhone or iPad, which give a page less memory), so a very large film at 600 dpi is made at a lower dpi instead, and the page says so. The art still prints at the width you set.

No. The design is read, separated and written into the films in your browser, and the files are saved from memory on your computer. Close the tab and nothing is left.