Riso printer, risograph, RISO Printer-Duplicator or also called simply only Riso is a stencil printer designed mainly for high-volume photocopying, duplicating and printing. It sits in the realm somewhere between screen print and offset lithography but with a unique aesthetic.
Traditionally, risographs have been used for high volume photocopying in schools, churches and small political parties. It uses soy based inks to produce unique quality outcomes, each screen is made from banana paper and unlike litho printing only takes a single print for the screen to be fully inked and ready for printing.
The underlying technology of a risograph is very similar to screen printing or a mimeograph. It works by creating a thermographic master screen for each colour of your artwork. This is then wrapped round a rotating drum. Ink is pushed through tiny holes in the screen and onto the paper, which is fed flat through the machine while the drum rotates at high speed to print each image on the paper.
The process works by printing one colour at a time. Multicolour images are created by switching the drum colour and running the paper through the machine again creating layers in a process similar to screen printing.
Maximum Size: A3
Printable Paper Sizes: 90x140mm to 280x435mm
Paper Weight: 60gsm - 250gsm
Stencil printers print up to A3 size. Irregular paper sizes can go through the machine, although those will have to be tested by printer prior to printing so please get an advise by your local riso printer.
Riso soy ink does not like gloss. Therefor risographic printers can print only onto a range of papers but must be uncoated and under 250gsm. There are exceptions though so please contact your printer to discuss any other options you may have.
Riso do not make cyan or magenta ink. Risograph printers are limited to a certain number of commercially available colours. It prints using specific spot colours so it is able to print colours that would be unachievable on digital printers, which use CMYK. These include gold or fluorescent pink. Beware that colour results do vary according to paper stock.
Colour references on Cyclus
Black – Neutral Black U
Federal Blue – 294 U
Medium Blue – 2738 U
Light blue – 3005 U
Purple – 275 U
Teal – 328 U
Green – 354 U
Yellow – Yellow U
Gold – 117 U
Orange – 1505 U
Red – Warm Red U
Fluorescent Pink – 906 U
Fluorescent Orange – 905 U
Burgundy – 7419 U
Hunter Green – 561 U
Brown – 7581 U
The riso colours are not 100% opaque so they are easily blended to make new colours. As well as blending the 100% tones of the colours, it is also possible to blend any combination of tints together to produce colour variants. This is advantage specially when you are planning to use third color that can be easily made out of combing the two colors.
By printing a greyscale image on any one of the colour drums you create a monotone, By combining 2 colours you can create a Duotone image.
It is also possible to imitate the CMYK print process by using the colours available. The yellow and black stay the same, we use blue instead of cyan which is slightly darker. and either fluorescent pink or red to replace magenta both give a full colour effect but the pink makes a much more vibrant image.
The risograph machine automatically processes greyscale images and applies a halftone screen with customizable LPI and angles. If you desire one type of halftone over another, you need to indicate the LPI number when submitting your job.
If you have a customized halftone screen, or a dither pattern, that you want to apply in printing, the best thing to do is to make your image with that halftone and export it as a 600 DPI Bitmap file. The printer won’t apply any halftone here, and will instead read the custom pattern that you’ve created!
The risograph is not perfect like a inkjet or laser printer. The prints will probably look different from what you see on your computer screen. There will be print marks, especially when printing more than one layer or double sided. But these can easily be rubbed off with a rubber.
Risographs are not designed for multiple colour printing, there will ALWAYS be a degree of mis-registration when printing several colours/ layers at the time, please bare this in mind when designing. Allow bleed and trapping to counter this.
The Machine uses rubber tires to feed the paper into the press. If there is heavy ink coverage already on the page the riso will leave tyre marks on the sheet but these can easily be rubbed off with a rubber.
Double Sided Marks
When printing double sided the feed mechanism will push the sheets together as it feeds the paper, this results in a small mark in the centre of the feed edge again this can be removed with a rubber. If there is particularly heavy coverage the image can smudge slightly as it goes through the press to print the other side.
Max paper size A3(297mm x 420mm)
with printable area 291mm x 397mm
All files must come in PDF format, 1 pdf for each colour, with crop, registration and bleed marks offset to 4mm, 10mm clear border
All images must arrive separated as JPG file, each layer must be greyscale, simply making each colour a different layer in your software of choice and then turning those into greyscale files. All images must be at the size intended for printing. The risograph will automatically convert your images into halftones or grains, so no need to play around with bitmaps.
Text and Shapes
When exporting text and line art to keep them as vectors and do not rasterize them. All type and solid shapes must to be set to RGB BLACK (R:0 G:0 B:0).
Color Space and Transparency
The documents 'transparency blend space' must be changed from the default CMYK to RGB.