I used the woven card collagraph plate sealed with shellac to print using Jo Sonja and Atelier artists acrylics mixed with Derivan Matisse Open Medium to extend the drying time of the paints.
Problems with cleaning the collagraph plate
It was ok until I came to clean the plate – at which point it became a disaster. I managed 5 prints. I did notice that the plate had become sticky after the second print but I thought that was the paint. Then I noticed that the smell had changed – not for the better. After 5 prints I decided to clean the plate. I submerged it in water and wiped with a cloth. The paint didn’t move so I scrubbed with a nailbrush. The paint and shellac all came off where the paint was in contact with the shellac – so the card absorbed quite a bit of water.
Where there was shellac only (around the edges and on the back) the shellac remained intact (even when it was scrubbed with the nailbrush). I can only conclude that something in the open medium affected the shellac (or maybe the medium in combination with paints from another brand). I must admit I was not using the Matisse open medium with the Matisse Structure paints for which it was intended so it could be the combination and not the open medium by itself that has caused the problem. I have left the plate in the sun to dry out as I quite like it as it is so it could be sealed once dry and re-used for another purpose.
I learnt that I should have tested the shellac as a waterproofing agent on some small pieces of the card rather than using it for the first time on a plate that took me several hours to make. Then I should have tested the painting medium on those samples. My reading had indicated that shellac was the way to go but most of the books I was referring to were pretty old – open medium and paints that can be “unlocked” have been developed since they were written. The information I had would have been written for plates that were intended to be used with printing ink (which at that time would have all been oil based I imagine). Now I do actually have some Derivan Matisse Structure paints and some of their Block Printing inks (water clean up is also a recent development) so I guess there is a whole new area of enquiry right there. The question is – am I ever going to actually produce any artwork or am I going to carry on testing for ever? 🙂