Printing watercolour with risograph

A few months ago I was experimenting with printing my watercolour images with risograph, and as I haven’t come across any other articles about this, I thought I might share the experiences. I printed a small watercolour portrait in three colours and daresay the result was successful – meaning that it looked nice.

So, let’s get to it. First, the technical data.

Risograph printer RZ 570EP, A3, with three colour drums – black A3, sunflower yellow A3 (which I’ll soon have to to change to orange or fluo orange) and medium blue B4. The different size of the blue drum means that in practice any print in three colours should be maximum B4 and ideally A4.

Scanner -Epson Perfection V37, A4.

Programs I use for colour separation and conversion – Irfanview v. 4.38 and Adobe Photoshop CS2. (As my laptop is old, it can’t really handle the newer ‘heavier’ versions)

The image I used was this little portrait in same colours as my colour drums – pure watercolour on cold pressed A6 (postcard size paper), no pencil lines.


I scanned it with 300 dpi resolution and ran directly into the main conflict issue between risograph print and watercolour, namely colour separation. Ironically, the same lightness and mixing of colours that gives watercolour its beauty and charm, makes its conversion into riso layers a proper pain in the neck.

However, magic wand in Photoshop, with tolerance upped to  78 (it needs a bit of playing around in order to find the best value) did a decent job. Not perfect, but decent Рluckily this type of watercolour painting does not need absolute exactness.


Clearly, none of the layers are separated cleanly, but for printing it didn’t actually prove to be a problem (in terms of the end result). I’m not sure whether it is an issue of the separation method I chose or it is simply inevitable that below a certain level of darkness, Photoshop doesn’t seem to distinguish between colour and value.

Anyhow, as the next step, I converted all layers to greyscale. For this I used Irfanview, as there it can conveniently be done with one click (I’m not particularly good with Photoshop, so I use Irfanview for most things). Values remained unchanged.


And then to risograph… Unfortunately I forgot to save the orange layer on its own, but together with blue it already looked pretty promising.


In fact, riso seems to duplicate the watercolour effect rather well. And after adding the final, black layer:


The black layer left a stripe down from the beret, but as the whole image doesn’t have exact lines, it almost seems organic. Now, let’s see both the original and riso print next to each other:


Everything considered, I’d say that it worked. I used ordinary copy paper to make the riso print, and quite probably¬†using a paper with some texture might have produced better results. Also, designwise, having the strongest colour (black beret) just at the upper edge of the image was a mistake, as it got stuck to the drum. Some space (from other experience, minimum 1 cm) at the upper edge is definitely necessary.

So. This was the success story. One of the next posts will be about the spectacular failure of using the same method on riso printing a comic.