post alternative techniques

**koraks** · 1-Jun-2015, 07:49

I'll run a test with classic cyanotype again, but when I started out with blueprinting, I found I needed very low contrast negatives, while I generally produce very high contrast ones today, as I want to use them for Van Dyke brown and carbon transfer as well.

Btw, I generally add one drop of 40% citric acid per ml of sensitizer; I've tried up to 3 drops, but I get weaker and weaker prints as I increase the amount of citric acid in the sensitizer. I might try a first rinse in 5% acetic acid. Tap water is too alkaline where I live; I always get a yellow-green stain when I don't acidify it a bit. With citric acid, I get prints with good density, clear highlights (perhaps too clear...) and a very pleasing tone, but the contrast is through the roof at that point, I also need to overprint heavily which blocks up the shadows. I may give adding dichromate another try, but previously I never got any good results with that. Staining, low contrast.

**Vaughn** · 1-Jun-2015, 12:09

I do platinum/palladium printing and carbon printing -- requiring negatives of different density ranges. I print pt/pd with no contrast agent (such as Na2, potassium dichromate or potassium chlorate), and need even higher contrast negatives for way I make carbon prints.

I find it easier and more productive to determine what process an image will be printing in, before I expose and develop the film. If I want to do it in both processes, than I make two negatives.

I do it this way to hit the 'sweet spot' for each process -- rather than try to tweak a process to its maximum to try to print a marginal negative. I feel that print quality can suffer when a process is pushed too far to match an unsuitable negative.

Edited to add: Also, since many times tweaking the process changes the way the print looks (color, etc), it is easier to match print characteristics for a consistent presentation, if that is an issue, if one's negatives are close in density range and over-all density.