A risograph is a stencil-based digital duplicator made by Riso Kagaku Corporation, a Japanese company founded in 1946 by Noboru Hayama. “Riso” means “ideal” in Japanese. The first Risograph machine was released in 1980, designed for high-volume office printing — schools, churches, community centers. It was never meant for art.

Artists found it anyway.

How It Works

A risograph prints one color at a time. For each color layer, the machine burns tiny holes into a paper master (the stencil) using thermal technology. The master wraps around a drum filled with ink. As paper feeds through, the drum pushes ink through the stencil holes and onto the sheet.

For a two-color print, you run the paper through twice — once per drum. Three colors, three passes. Each pass introduces slight misregistration: the paper shifts a fraction of a millimeter, so layers don’t align perfectly. This is a feature, not a bug.

The Ink

Risograph inks are soy-based (or rice bran oil-based), not petroleum-based. They’re semi-transparent, which means overlapping two colors produces a third. Blue over yellow gives green. Pink over blue gives purple. The transparency is what makes overprinting possible and what gives riso prints their characteristic layered depth.

The inks never fully dry. They absorb into uncoated paper rather than sitting on top of it, which is why riso can only print on uncoated stock. Touch a fresh print and it will smudge slightly. This is permanent — riso prints will always have a faint tactile quality.

The Color Palette

Riso doesn’t use CMYK. Instead, it uses spot colors — each drum holds one specific ink color. There are 77 documented ink colors, though most print shops stock 8–15. The full catalog, sourced from the riso-colors npm package and Stencil Wiki:

Reds & Pinks
#f65058ScarletWarm, slightly orange.
#f15060Bright RedClose to Scarlet, slightly cooler.
#ff665eRedWarm red, coral-leaning.
#e45d50CrimsonEarthy, brick-adjacent.
#d2515eMarine RedMuted, dusty red.
#d2515eTomatoSame hex as Marine Red.
#a75154BrickDark, earthy.
#d1517aCranberryPink-red, berry tone.
#d1517aRaspberry RedSame hex as Cranberry.
#9e4c6eMaroonDeep plum-red.
#914e72BurgundyWine-dark.
#914e72WineSame hex as Burgundy.
#ff48b0Fluorescent PinkThe signature riso color. Neon, electric.
#ff4c65Fluorescent RedNeon red-pink.
#ff7477Fluorescent OrangeCoral-leaning. Glows under certain light.
#f984caBubble GumBright candy pink.
#e6b5c9Light MauvePale dusty pink.
#bd8ca6Dark MauveMuted rose.
#f2cdcfBisqueNear-white blush.
#ff8e91CoralSoft salmon-pink.
Oranges & Yellows
#ff6c2fOrangePumpkin. Warm and saturated.
#ff6f4cPumpkinSlightly lighter than Orange.
#ee7f4bPaprikaWarm spice tone.
#f6a04dApricotSoft, warm peach-orange.
#ffae3bMelonGolden amber.
#ffb511SunflowerBright, clean. Overprints well with blue.
#ffe800YellowPure, vivid yellow.
#ffe900Fluorescent YellowNeon yellow. Nearly identical to Yellow.
#e3ed55Light LimeYellow-green, chartreuse.
#b49f29Bright Olive GreenDark olive-gold.
Golds & Browns
#bb8b41Flat GoldMatte gold, no metallic sheen.
#ba8032Bright GoldWarmer, deeper gold.
#ac936eMetallic GoldActual metallic sheen on paper.
#bd6439CopperWarm metallic brown.
#925f52BrownWarm, earthy.
#8e595aMahoganyDark reddish-brown.
Greens
#44d62cFluorescent GreenNeon, electric green.
#67b346Kelly GreenClassic bright green.
#00a95cGreenGrass green, slightly warm.
#19975dEmeraldRich jewel green.
#169b62IvyDeep, saturated green.
#397e58GrassDark, muted lawn green.
#516e5aForestDark, desaturated.
#4a635dSpruceBlue-green, very dark.
#68724dMossOlive-green, earthy.
#5e695eSlateGray-green.
#407060Hunter GreenClassic dark green.
Teals & Aquas
#62c2b1Sea FoamLight, minty.
#82d8d5MintPale, airy teal.
#00aa93TurquoiseVivid blue-green.
#009da5Light TealBlue-green, darker than you'd expect.
#00838aTealDeep, classic teal.
#237e74PineDark teal-green.
#2f6165LagoonVery dark teal.
#5f8289Smoky TealMuted, gray-teal.
#5ec8e5AquaLight, airy. Needs dark text.
#d5e4c0MistPale sage-green. Nearly white.
Blues
#62a8e5CornflowerLight, friendly blue.
#4982cfSky BlueMedium, slightly muted.
#0078bfBlueThe workhorse. Deep, slightly cyan-leaning.
#0074a2Sea BlueDarker, greener blue.
#235ba8LakeDeep, rich blue.
#3255a4Medium BlueClassic mid-blue.
#3d5588RisoFederal BlueMuted navy.
#375e77SteelBlue-gray, industrial.
#484d7aIndigoDark blue-purple.
#435060MidnightBlue-tinted dark grey.
Purples
#9d7ad2VioletMuted, more grape than lavender.
#aa60bfOrchidBright, warm purple.
#765ba7PurpleClassic mid-purple.
#845991PlumDark, warm purple.
#775d7aRaisinMuted, dusty purple.
#6c5d80GrapeDark, desaturated.
Neutrals
#000000BlackTrue black.
#70747cCharcoalDark neutral gray.
#88898aLight GrayMid gray.
#928d88GrayWarm gray.
#a5aaa8GraniteCool, light gray.
#ffffffWhiteOpaque white ink.

Hex values are approximations — riso inks don’t conform to any digital color standard. They look different on different papers, at different ink densities, and under different lighting. The hex codes from Stencil Wiki and the riso-colors npm package are the closest community-maintained references.

Overprinting

Because the inks are transparent, layering two colors creates a third. This is the core creative technique in risography. A two-color print (say, blue and fluorescent pink) actually gives you three colors: blue, pink, and the dark magenta where they overlap.

Designers working with riso think in layers, not in final colors. You separate your artwork into individual color channels — one grayscale image per ink color — and the machine prints them sequentially. Where the layers overlap, the inks mix optically and physically on the paper.

This is fundamentally different from CMYK printing, where four inks are applied in precise halftone dots to simulate continuous color. Riso overprinting is coarser, more visible, and more unpredictable. That’s the appeal.

Why It Looks the Way It Looks

Several mechanical properties combine to create the riso aesthetic:

Misregistration. Each pass through the machine shifts the paper slightly. Layers don’t align perfectly. This creates the characteristic “offset” look where colors bleed past their intended boundaries.

Grain and texture. The stencil process produces a visible dot pattern, especially in midtones. Solid areas have slight variation in ink density. Nothing is perfectly flat.

Ink absorption. Because the ink soaks into the paper rather than sitting on top, colors appear slightly muted compared to their digital hex values. The paper color (usually off-white or cream) shows through.

Limited palette. Working with 2–3 spot colors forces graphic simplicity. You can’t reach for a gradient or a subtle tonal shift. You work with flat color, overprint, and halftone.

Riso Color in Digital Design

The riso aesthetic has migrated from print to screen. Designers use riso-inspired palettes in web design, illustration, and branding because the colors have a specific character: saturated but not neon, vibrant but not digital-feeling, limited but expressive.

When translating riso colors to digital, a few principles apply:

Avoid pure primaries. #ff0000 is not a riso red. Riso colors are always slightly shifted — warmer, cooler, or more muted than their pure hex equivalents. The red is more brick than fire engine. The blue leans cyan, not cobalt.

Keep saturation high but not maxed. Riso inks are vivid, but they’re printed on absorbent paper, which softens them. In digital, this translates to colors around 60–80% saturation, not 100%.

Limit your palette. A riso print rarely uses more than 3–4 colors. The constraint is what makes the aesthetic work. In digital, this means picking 2–3 accent colors and a neutral, not a rainbow.

Think about overprint. If two of your colors would overlap in a print, what color would they make? Good riso palettes produce pleasing overprint combinations. Blue + yellow = green. Pink + blue = purple. If your palette’s overlaps produce mud, reconsider.

Sources