I noted which inks I used below and the bottom row of each pair is 50/50 extender and ink, the top row is just ink. The group discussions often commented that red was the slowest drying color so I compared two different reds; naphthol and rubine. All inks are caligo safe wash oil based relief inks, and the paper is Fabriano Rosapina.
This was very, very useful. I first of all learnt that the naphthol red gave a much smoother print, the rubine was quite patchy. This is not very clear on the photo of the sample below, but there was a big difference.
I was surprised by how the greens came out.
The process blue (cyan) made a very bright green, I got a much better color with the prussian blue. These inks are so intense that color mixing can be really hard. To create green I used tiny, tiny amounts of blue and still got a very dark green.
When I got to the darker layers the 50/50 extender ratio was too transparent, but pure ink was a bit patchy, this did not make much difference to drying time.
I used this as an opportunity to practice blotting between layers, something I have not done before. I tried a few papers but found construction paper and pressure from a brayer most effective.
As to drying time, I left 24 hrs between layers and up until the last layers that was long enough for all layers to be dry before applying the next coat. There is 7 layers in total and only the last two, blue and brown/black took longer than 24hrs to dry. However, these last two layers are still tacky a week later. I think the absorbent Rosapina paper helped, I've made other multi-layered prints on less absorbent paper with much slower drying time. Possibly by layers 6 and 7 the paper cannot absorb any more ink?