Color separation

For stencil based printing with multiple ink color layers, color separation helps bring the original artwork into the layers (usually greyscale) used to make each stencil. This can be done by hand, analog or digitally.

There are also a number of apps, websites, and other tools that help with color separation, especially for artwork that is already made, such as a photograph or painting.

Methodologies

There are many different approaches to color separation, here are a few distinct ones:

1. Using riso specific tools, to get quick and easy, full color processing, using the ink colors employed by the riso.
   • Spectrolite, a free Mac desktop app (which also includes a lot of other production tools for risograph publications).
   • Stochaster Apps, a suite of apps for processing images that includes Coloraster for separation.
   • Risotto's online print simulator.
   • P5 JS riso
   • Graintouch for iPad somewhat aimed at making faux-riso look digitally, but offers some color separation features.
2. Creating separations while making the artwork by hand layering, either digitally or analogue with transparency/translucency.
   • In this method each layer is dedicated to a single ink (often created in grayscale), rather than creating something full color which is then separated into inks.
   • An analogue version of this can be done using layers of tracing paper or translucent vellum (following some methods of screen printing or other manual color separation).
3. Using a palette of color mixes which are pre-planned through color charts.
   • Both Natalie Andrewson and Ryan Cecil Smith do different versions of this (see below).
4. Starting with RGB or CMYK and then channel shifting—to map each channel to a riso color.
   • This can be done manually in a tool like Photoshop or GIMP, or anything else which gives channel access in addition to just layers. The channels are split apart and then colorized to match riso ink colors (and usually previewed with a "multiply" blending mode or something similar.
   • The risoseparator.tools online tool also uses this process.
5. Using ICC profiles—bits of software that are used in production workflows to map different inks to digital files, built by analyzing printed test swatches (this is the workflow used in a lot of commercial printing and offset that uses custom process colors).
   • Color/shift is doing a lot of this work in the risograph community, and has a lot of tutorials and teaching around making and using profiles. They offer both profiles and training with the *CMYKinda course series.
   • en.exploriso.info/exploriso-colour-profiles
   • Risolve offers color profiles and an accompanying tutorial video.
   • ColorLibrary.ch has profiles for purchase as well as a tutorial on using ICC profiles and color spaces.
6. Using a duotone or tritone process on a greyscale image.
7. Similarly using a posterizing filter to separate an image into spot colors.
8. Using an analog photography method (screening colors out with filters).

Other resources

• Virtual overprint charts from Issue Press.
• Exploriso has an in depth guide to risograph color, including detailed guides on many methods for creating separations.
• Colorama has a guide with a color separation section.
• Risotto offers tools and a set of how-to guides.
• Natalie Andrewson's patreon has many tutorials for her method of color separation.

Books and zines

• Dreaming in Color by Natalie Andrewson, PEOW2.
• Exploriso: Low Tech Fine Art by Sven Tilkak.
• Layers4Players by Chloé Barbier, Colorama—a hand-book about digital file-prep in Photoshop for riso-printing.
• InDesign4UnDesigners, Johanna Choultz, Colorama—a hand-book about layout, margins and file-prep in InDesign for riso-printing.
• The Color Sciences Multipack from Ryan Cecil Smith which walks through creating a set palette and processing method from Copic marker originals to riso-printed final colors.
• Making a zine and riso printing it with Spectrolite and Google Docs, Amelia and Adam Greenhall, ANEMONE—a tutorial about writing and designing in Google Docs, laying out for printing in Spectrolite, printing on a home/office printer, how to do color separation and file prep for risograph printing, and lots of tips and ideas along the way. Free print-your-own or edit further and publish your own version files available.

Related concepts

There are also other concepts related to color separation that can be useful to understand, such as:

• Trapping
• Total Area Coverage TAC
• How to flatten files to reduce artifacts from printer drivers
• Halftones and choosing halftone angles