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Spot colors, foil, white ink & spot UV explained
A metallic foil logo, a glossy raised varnish, a white underprint on kraft stock, a die line that tells the machine where to cut — none of these are made of CMYK ink. Each is its own printing plate, and your printer needs it marked as a spot color with exactly the name they expect. This guide shows you how to set up each finish in Popcorn Editor and export it as a real separation.
Beyond the four inks
Process printing lays down four inks — cyan, magenta, yellow and black — to reproduce almost any color. But a special finish is applied by a separate unit or a separate pass: a foil stamp, a UV varnish station, a white ink head, a cutting die. The press can't mix those from CMYK. Instead, you hand over an extra plate that says "put the finish exactly here." In a print file, that plate is a spot color.
What a spot color is
A spot color is a named separation the press treats as its own plate or ink, not blended
from process inks. In Popcorn Editor, a swatch is typed as either Process or Spot. A
process swatch is just a named CMYK color. A spot swatch carries a name that becomes a
PDF Separation colorant on export — so Foil stays Foil all the way to the RIP instead
of collapsing into cyan-plus-magenta.
The on-screen color you see for a spot is only a preview ink — a soft-proof so you can work with it. The real appearance comes from the physical foil, varnish or die on press.
Create a spot swatch with a Purpose preset
Open Swatches in the Properties panel and add a swatch, then set its type to Spot. The key control is Purpose — a preset that fills in the name and the preview ink that print services conventionally expect:
| Purpose | Typical use |
|---|---|
| Die cut | Cut all the way through the stock |
| Cut line | A generic cutting contour |
| Kiss cut | Cut the vinyl but not the backing (sticker sheets) |
| White ink | White underprint or standalone white |
| Varnish | Protective or decorative coating |
| Foil | Metallic or pigment foil |
| Spot UV | Glossy raised UV coating |
| Custom | Anything else — a Pantone, a scodix, an emboss |
As the in-app hint puts it: "Presets fill in the name and preview ink print services expect. The name stays fully editable." If your printer asks for a specific colorant name, type theirs over the preset.
Foil & spot UV
Foil is a metallic or pigment film pressed onto the sheet; spot UV is a glossy varnish raised over a matte background. Both are pure "put it here" plates.
The workflow is the same for either: draw the shape that defines where the finish goes — the outline of a logo, a band across a card, a pattern — and fill it with your Foil or Spot UV spot swatch. Keep it as a clean vector wherever you can; foil and UV reproduce crisp edges beautifully but hate soft gradients and fine anti-aliased detail. The shape's job is to be a mask, not a picture.
White ink
On clear, dark or kraft stock, colors printed straight onto the material look dull or vanish, so a white ink layer is printed first (an underprint) to give the CMYK something bright to sit on — or on its own as a design element. Use the White ink preset. Like the other technical inks, it defaults to Overprint, which matters: a white underprint needs to sit with the artwork, and depending on the job you may want it under the color rather than knocking a hole in it. Confirm the exact behavior — underprint vs. overprint white — with your print service.
Die cut, kiss cut & cut lines
A cut shape belongs on its own spot plate too. The fastest path is built for it: select the object whose outline defines the shape, then open Make cut contour in Properties. Set the Offset (0 mm sits exactly on the edge; a positive value grows the cut outward) and the Type — Die cut, Cut line or Kiss cut — then click Create cut contour.
In a hurry, Object → Make cut contour applies a one-click 3 mm die cut with the same
result. Either way you get a path on a dedicated spot swatch (for example Die Cut), set to
overprint so it marks the cut without punching a hole in the art beneath. Kiss cut is the
one for sticker sheets — it cuts the material but leaves the backing intact.
Overprint — the setting that saves the job
This is the detail that trips people up. By default, printing one object over another knocks out the ink below it — the press leaves a hole so the colors don't mix. That's right for opaque CMYK, but wrong for a technical ink. A die line, a varnish or a white layer must Overprint, so it marks the sheet on top of the artwork without cutting a gap in it.
The Purpose presets already set overprint on for you, but always verify it. As the app reminds you: "Technical inks (die lines, varnish, white) usually overprint so the artwork beneath prints intact." At export, keep the Overprint / rich black option on so that behavior carries through to the PDF.
A varnish or foil that doesn't overprint will knock a white hole in your design exactly where the finish should be. If a proof shows a gap under a finish, overprint is the first thing to check.
Naming matters
Print services match spot names case-sensitively — Foil, foil and FOIL are three
different plates to a RIP. Popcorn Editor guards this for you:
- It warns when a name "differs only by case from another spot color."
- It warns when a spot name "matches a process ink" (Cyan, Magenta, Yellow, Black, Registration) — which would merge it onto that plate.
- It rejects the reserved separation names All and None outright.
Use the exact name your printer specifies. When you don't have one, the Purpose presets give you conventional names most services recognize.
Export as real separations
One hard requirement: spot colors only export as true separations from a CMYK document. In RGB mode they flatten to their preview values — you'll get a picture of the finish, not a plate for it. The app flags this directly: "This document is in RGB mode. Spot colors only export as separations from CMYK documents," with a one-click Switch to CMYK.
With the document in CMYK, export a Print (CMYK) PDF and read the Print checks panel before you click through. It warns if a spot would be lost or rasterized — for example a spot color sitting under an effect, mask or gradient will be flattened to process CMYK, and it tells you which objects. Clear those, and every finish reaches the printer as its own clean, correctly named plate.
Next
Ready to put it into a file? Follow the click-path in How to export a print-ready PDF, and run the full pre-flight checklist before you hand off. For the underlying reference, see Spot colors & print separations and Cut contours & dielines.