I’m just starting with cyanotype and after few tests I thought it might be a good idea to write down some preliminary results.
I say preliminary because it will continue. I want to test different emulsion formulas as well as different light sources to find the best approach for my project. Let’s start with emulsion formulas. For the beginning I selected four formulas based on this book but there are plenty other resources to find them. Below table shows basic formula (a) and calculated reduction (b) just to save ingredients.
- PF stands for potassium ferricyanide
- FAC stands for ferric ammonium citrate (green)
- Water is distilled – do not use tap water
Yesterday (05.05.2018) I prepared emulsion 1b and stored it in a brown plastic container so there is no light leakage.
I also covered part of two A5 250g sheets of Clairefontaine Paint’On acid free paper. One was developed almost immediately because sun was still shining at 7:12 pm and the other was left for the next day to dry slowly in darkness of the night. Immediate development means that hairdryer was used. Some say you shouldn’t use one because dust and chemicals can collect on emulsion … but who says you should blow on the emulsion? You can dry paper quickly blowing on the other side so there is no risk of any kind damaging emulsion. That said I made myself my first A to Z print.
Formula 1b, Sun exposure time 20 minutes, no clouds. Final development in water 500ml and hydrogen peroxide 1ml to boost a little this fantastic Prussian blue.
Today (06.05.2018) weather was perfect so I made additional 6 prints testing mainly exposure time. In every case the formula is 1b, Sun was the light source and final development bath was water with hydrogen peroxide at the ratio 500ml/1ml.
As you can see results are more or less as expected … except two prints. As I said weather was perfect, clouds were only in the horizon but still there might have been some temporary unseen coverage because print 7 should be darker than print 5. Exposure time of print 7 was a minute longer and it’s still a bit lighter than 5. If I needed to choose one I’d say that print 7 has more details and levels are ok but it doesn’t translate to exposure time.
I’ll be still testing Sun exposure tomorrow but probably later than today, maybe around 5 pm and all sheets will be prepared and dried upfront.