The risograph separation tool splits your image into one grayscale layer per spot ink, ready to print on a risograph or screen-print press. This page covers the inks, how the separation is calculated, what is in the ZIP, and how to get a good print.
A risograph prints one ink at a time. Each color gets its own drum and its own master (a stencil burned from a black-and-white file). To print a two-color poster, you need two files: one that says where the pink goes, and one that says where the blue goes. That is exactly what this tool makes.
Each layer is a grayscale image where black means full ink and white means no ink. Greys become partial coverage, which the risograph turns into its own screen or dither when it makes the master.
zip).The "risograph separation" window opens with a live preview of the printed result on white paper, a thumbnail of each ink layer, and the ink list.
Note: Separation works from your original image, not from the current effect. Dither, halftone and other effects are not carried into the layers, because the risograph applies its own screening when it makes each master.
Click an ink to add it, click it again to remove it. You can use between 1 and 4 inks. The tool starts with Fluoro Pink and Blue, the classic riso pairing. It will not let you remove the last ink, and it ignores clicks past the fourth.
| Ink | Approximate color |
|---|---|
| Black | Soft black |
| Fluoro Pink | Fluorescent pink |
| Blue | Medium blue |
| Yellow | Bright yellow |
| Red | Warm coral red |
| Green | Emerald green |
| Purple | Violet |
| Teal | Deep teal |
| Orange | Bright orange |
The preview updates a moment after each change. The line at the bottom reads, for example, "2 inks ยท exports a zip of print-ready layers".
Think of each ink as a filter that removes some light from white paper. Fluoro Pink removes mostly green, Blue removes mostly red, Yellow removes mostly blue, and so on. For every pixel, Bitgrain asks: how much darker than white is this pixel, and in which direction? Then, for each ink, it measures how well that ink's own darkening direction lines up with what the pixel needs. That match becomes the ink's density at that pixel, from 0 (no ink) to 1 (full ink).
A few consequences are worth knowing:
The preview works on a copy of your image up to 900 px on the long edge, so it stays quick.
Click export zip. Bitgrain separates the image again at up to 2,400 px on the long edge on Pro, or 1,500 px on the free plan (smaller images are not enlarged), then downloads a ZIP named bitgrain-riso- followed by a timestamp.
On the free plan, the preview and every ink layer in the ZIP carry the small bitgrain.app watermark in the bottom right corner. Because it sits on each layer, it prints in every ink. Pro removes it.
Inside:
| File | What it is |
|---|---|
preview.png | The full-color preview of the inks overprinted on white |
01-fluorescent-pink.png | The first ink's layer |
02-blue.png | The second ink's layer |
03-...png, 04-...png | Further layers, if you chose more inks |
Layer files are numbered in the order you selected the inks and named after the ink: black, fluorescent-pink, blue, yellow, red, green, purple, teal or orange. Every layer is a grayscale PNG the same size as the others, so they line up exactly when stacked.
Tip: For a riso look on screen without printing, try the Risograph palette with a dither, or the /risograph landing page, which opens the editor with a dither and grain look.