Adjusting a hand-drawn psychedelic poster to riso printing – Part 1

Well, it’s been a good while since the last riso experiment blog post and hence high time to do something about it. And this was simple enough – as I’m organizing open live drawing sessions, I also make a new poster every Sunday to advertise it on Facebook. (Still not sure how well it works, but never mind that right now.)

Anyhow, with the last one I decided to ditch the ‘modern’ poster aesthetic and go with the style I actually love and make it look like the flat colorful psychedelic 60’s posters that couldn’t care less whether the viewers can read them or not.

So, first I made a sketch, inked the lines, scanned it and colored it in Photoshop and was done with the poster for original purpose. Fine, fine. However, the original line drawing was still there, so I figured there can be no harm in coloring it a bit. Besides the super-multi-color psychedelic style, I’m a great fan of its Art Deco predecessor – mono- and duo-chromatic images, that are colored only with different tones of the same color or different tones of two different colors that form a mosaic instead of mixing or overlapping. Having in the back of my mind that this technique is in many way perfect for riso printing AND that my only usable drum at this moment is fluo orange, I went ahead and colored the poster with three different orange markers (and black, which I intended to add to riso print later with stencil).

Here they are – the original, the colorful and the monochrome version.


*The monochrome one is on peach-colored paper.

Now, the question arose – how to turn the monochrome version into a riso-printable one. Just converting the scanned image into grayscale is simple but does not print well, because the marker-colored parts are not evenly filled. Quality-wise it made better sense to use the monochrome version as a guide and color the ‘clean’ version again digitally for better quality. My original idea was to go for the Art-Deco style duo-chrome and print it on blue paper (as I had some). This way blue would act as the darker contrast to the fluo orange, lighter tones of fluo orange would overlap blue and soften the contrast. At least that was the idea.

In order to make the process easier, I started by filling in the original clean background areas with blue. The rest are different tones of the original “Live Drawing” text orange. (I use the super-handy site 0to255 for finding tone gradations.). I replaced all black parts with white (in my CS2 – Image -> Adjustments -> Replace color), as those I wanted to add with stencil later. Next step, I replaced the blue parts with white as well, because that was to be the color of paper and finally converted the image to grayscale.


And made a couple of test prints on different papers.

Test prints revealed a lot – mostly design mistakes. The blue paper was way too intense – I had underestimated the natural semi-transparency of riso ink. (After all it’s not acrylic or tempera.) All the softer tones were completely overpowered and even full coverage looked rather weak. Yellow and peach-colored papers produced delightful surprises. Yellow, that I had not even considered as viable option and only tried because it happened to be at hand, produced the best contrast and color combination of all. The scan unfortunately doesn’t do it justice. Peach-toned paper came in second, although the background tone blended at bit too well with the softer tones of fluo orange and hence the contrast was not the best.


The last test print was on white paper to allow for corrections. So, here’s what I’m going to change in round 2 (left is test print and right one with corrections) – get rid of most soft tones and go for maximum contrast (and fix the “shift to the right” that my printer tends to do…)


To be continued…

Cleaning up hand-drawn images for riso printing

A quick, yet important note on printing hand-drawn images with risograph. Even if the drawing looks nice and clean in RGB, it is (apparently) NOT enough simply to scan and print. Because…



This lovely grey haze around the edges, yes. Invisible if you zoom in on the RGB image on the screen and very visible, when riso printed. Zoomed in, it looks like this:


However, good news is that there is a rather simple (and meditative) way to get rid of them. Assuming the image is originally saved in RGB, open it in Photoshop (I have CS2, but I think these functions are still in the same place in the new versions), choose ‘Image’ -> ‘Mode’ -> ‘Greyscale’. Say ‘yes’ to discard colour information and voilá, now the image is in greyscale. Then go back to ‘Image’, choose ‘Mode’ and ‘Bitmap’ to convert it to black and white only. When saving the image, you’ll be asked about the type of coverage you prefer. In this case I used ‘Halftone screen’, but from image cleaning point of view, it does not matter which one you choose. Now, with the image in bitmap, zoom in to 300%, choose a good eraser size (I switched between 4-12px) and get to cleaning. It gives about the same level of satisfaction as cleaning dirty windows, so it’s a great meditative task for anxious days. After the pesky extra pixels are all cleaned up, I’d recommend to switch to brush about same size or smaller (2-5px) and fill in the white gaps on the black areas. When this is done, you’re done and can either save the image in bitmap or convert it back to greyscale.

rose card clean.jpg

And the text looks now like this:


There you go.

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 – luckily 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.