Gast
Hello,
I have been using Classic Art Polywarmton in both the baryta and RC versions for quite some time now. I have often toned both papers with sepia toner – so far without any problems, whether using shop-bought toner or a mixture I have made myself.
I recently received a new batch of CA Polywarmton RC and have suddenly run into huge problems: all the white areas of the image (including the wheels covered during exposure) are always turning brownish, sometimes evenly, sometimes patchy. At first I thought there was something wrong with my toner, but then I ran a sheet from an older (approx. 1.5 years old) box of CA PW RC and one from a new box through the process at the same time, and the old sheet was fine, whilst the new one was brown at the edges (everything looked fine before toning).
I’ve since switched to double fixing with two baths of Unifx liq. 1+4 and have freshly prepared all the baths. The stronger fixer has reduced the problem somewhat, but it hasn’t gone away completely.
Do you have any idea what can be done, and where does the difference between the old and new Polywarmton RC come from?
Best regards, Jens
P.S. I received four boxes (with two different emulsion numbers). Always the same problem.
Gast
Hello Jens,
We have passed this question on to Forte.
It’s too specific for us to be able to test it ourselves.
As for the emulsions: we only ever receive a few boxes of each emulsion type from Forte.
If we order 50 boxes, it’s usually spread across 2–4 different emulsion numbers.
I think this is because they don’t cut a whole roll into 50x60 sheets as it wouldn’t ‘work out’ width-wise.
Instead, different formats are combined so that they can be cut with as little waste as possible.
That’s why there are so many different emulsions.
However, as these come from a single production run, there shouldn’t be any major differences within a single delivery.
Best regards,
Mirko
Gast
Hello Jens,
Apologies for the delayed reply, but we had to carry out several tests.
It turns out that this common phenomenon is not dependent on the type of paper, and that it only becomes apparent during the drying process. This means that it is what is known as a ‘silver haze’.
The cause of this phenomenon is still under investigation. It may occur occasionally, but it does not depend on whether the FPW paper is an older or newer variety.
Based on our experience in laboratory tests, this phenomenon can be significantly reduced by using a stop bath after development: a 1.5–2% acetic acid solution (for approx. 30 seconds).
We hope this has been of some help.
Best regards,
Mirko
Gast
Hi Mirko,
After a fair bit of trial and error, the problem has now been sorted out. The solution is:
1) Two-bath fixing
2) Rinsing for longer than before
Incidentally, the differences between the paper batches were reproducible. I ran a sheet from the old batch and one from one of the new batches through the belts at the same time on several occasions, and the old one was always fine, whereas the new one had spots.
But, as I said, everything is fine now and there’s nothing to stop me using the paper again. Could it be that the base paper for Polywarmton RC has changed at some point? I’ve also noticed differences when writing on the reverse side. That might also explain the different behaviour during rinsing.
Best regards, Jens
