Today I painted emulsion on sheets in the morning 8 hours before exposure so it had time to dry slowly … and it turned towards green … lime-ish color. Normal color is yellow. Tomorrow if weather continues to cooperate I’ll test whether it has any impact on exposure. Of course to be 100% sure I’ll test it again with uv lamp in June.
So as you see below there is no significant difference between prints, I’d even risk statement that there is no difference at all for this type of printing. The weather was stable, no clouds but little haze, exposure times 5-6 minutes between 3:35pm – 4:40pm.
The only difference is that the last sheet (11) was different :) I used Canson sketchbook 160g just to check how lower density paper works … and it works just fine. It has a visible texture but apart from that no impact on prints.
One additional comment after two days of printing. In most of instructions on the internet regarding processing cyanotype prints you can read that rinsing after exposure should take few minutes (usually 5) under running water to get rid of yellow not exposed emulsion residue. The truth is it takes 30 to 40 seconds tops! Just put the print under running water and observe, once you don’t see yellow residue on your print you’re done! Make a final bath in hydrogen peroxide if you use it, again 10 seconds max, and your print is ready. I’m processing part of A5 sheets but even A4 shouldn’t take more than 1 minute … but I’ll check it anyway! :)
Hint: drying wet paper. I’m using printer’s method to deal with wet paper which I found on some forum by freaking accident. If you do not dry the paper under press it will bend so it appears that best solution is to do as follows:
- on a flat surface (desk) place a sheet of printing foil,
- put a print on it exposed side down,
- on print put few sheets of printer paper – I put 10,
- cover it with sheet of printing foil
- press everything with something flat like thick paper folder and put something heavy on it … laptop may do the trick ;)
Adding foil slows down a little drying process but works evenly on the whole surface and sheet comes out as new. Below is an example of print left for drying without press (left) and one made today which I treated as described above. Total drying time for A5 sheet is about 4 hours.
BUT! Before you put it in the press you have to get rid of excess water. After all baths are done, put your print on cotton towel and gently press with paper towel until sheet turns matt … then use the press.