So this isn’t exactly a support problem for PiezoDN specifically but I am using PiezoDN and wanted to reach out to the community here to see if anyone has seen this before.
Using the same process, chemistry, coating technique and the same target negative I printed the 129 step chart onto both Hahnemühle Platinum Rag and Ruscombe Paper Herschel Platinotype.
The Hahnemühle chart is looking good but the Ruscombe paper is looking very faded, blotchy and has very little contrast (it also has a nasty crease that my vacuum frame seems to be adding 
but that’s a separate problem).
Has anyone used this Ruscombe paper with cyanotype? I think it should be fine since it is unbuffered (and designed for platinum printing) so I am very confused. Any ideas are appreciated
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This looks like you either need to subtract or add tween20 to me. Others may have much more knowledge though.
best,
Walker
Thats a good thought. I’ve never used tween before so it might be worth giving it a try now, thanks
I agree about using Tween.
Also, looking at the exposed outer edge, you didn’t reach Dmax under the film. It looks to me like you need to double the exposure time. Don’t assume that an exposure time for one paper will be the same for any other paper. Last fall I did a bunch of testing with Ware’s New Cyanotype formula and found a range of exposure times from 3-12 minutes among the 12 papers I tested. Herschel was one of the fastest, but if you are using the classic formula that has no bearing. I should note that I was using a 4x5 21-step Stouffer tablet, not PiezoDN or any other digital negative.
I did make a limited and linearized PiezoDN quad for Platine, and made a few very nice prints with it, but that was as far as I got before getting back to my regular Pt/Pd work.
Which cyanotype formula are you using?
Thanks for the info Keith. I did indeed make the assumption that both papers would require the same exposure - that explains a lot now that I think about it. I’ll work on finding the correct time this week.
I’m using the classic formula. For these I mixed up 4ml for each print and dipped and painted the solution on. How much tween would you say is a good starting point for that amount of solution?
Try 1 drop of 10% Tween 20 per ml of total solution. Some papers may like more — I use twice that amount for HPR with its very hard surface; others may like less — Platine 145gsm and most Japanese papers need none. This is based on my Pt/Pd experience, though I expect it would hold for cyanotype or any process with a water-like viscosity.
