Risograph duplicators work like photocopiers but use a process that is similar to silkscreening. “Riso” is both the company that makes the machine and printing process, which was developed in Japan in the 1980s. It’s known for high-speed and low-cost printing, making it ideal for jobs between 500 – 1000 sheets. Normally found in schools and churches, artists around the world have started to use Risograph for its ability to develop vibrant prints and publications at a lower cost than commercial printers. Riso is ideal for zines, books, posters, postcards, and art prints.
Riso uses real ink, much like offset printing, instead of toner that requires heat to imprint on paper, like inkjet and laser printing. Riso ink is soy and rice bran based, which helps give inks its vibrancy, though that also means Riso can only print on uncoated paper, otherwise the ink won’t dry and adhere. Riso inks are translucent, allowing inks to be layered to produce ranges of colours, much like offset printing and silk screening.
How it works
The machine makes tiny holes through a fibre-based master using thermal plates. The master is adhered to a big drum, which contains the ink. The ink is then pushed through the holes in the master and rolled onto the paper.
Imperfections are part of the printing process, especially when using more than one colour. This is due to the way paper is fed through the machine and the way the master adheres to the drums. Rather than machine-precision, the charm of Riso is the way the ink sits on the paper and how the registrations are never perfectly aligned.
Roller marks and smudging happens when prints are fed into the machine again before the ink settles and dries. As the ink never dries, these marks and smudging could happen no matter how long you dry it. Paper with greater fibre content such as vellum, newsprint, and rice paper do better at retaining ink. But paper with too much texture will have a harder time being printed on, as the fibres inhibit ink from contacting the paper at high speeds. So the best paper is one that is absorbent and smooth.
Lines, shapes, and text work really well with Riso. The machine is able to read vector files and differentiate them from images, resulting in very crisp and clean lines. Non-vector images also come out well, as this machine can reach up to 600dpi.
Though Riso is not normally a process used to develop high resolution and accurate photos, Riso can print photos through layering colours via simulating the “CMYK” colours or experimenting with other colour combinations to replace the CMYK. A basic match to the traditional CMYK is mint, fluorescent pink, yellow, and black. Similar to photographic reproductions in silkscreen, you will get rich textures and experimental colour layers.
As it’s a duplicator, the machine comes with a scanner scan bed with robust image controls such as settings specific for photos and line documents, density, opacity, and changing the size. Scanning works best with documents that are primarily words, lines, and strong shapes.
For more complex jobs such as books and posters, files need to be set up so the machine can read it. Riso machines can’t read colour, it instead registers each colour as a grayscale layer. Files need to be converted to grayscale to achieve the desired effect during printing.
If you are using Indesign, you have to assign spot colours to each object and export it into a PDF.
Example of files you send for 4-colour print in grayscale:
What it will print as with corresponding ink: