View Full Version : is it possible to remove pyro stain?

27-Oct-2007, 05:40

Yesterday after processing my film I noticed a weird "sediment" on my negs that could only be removed by either rubbing it off (bad idea) or by using a rather powerful stream of water. I didn't think anything of it until I saw the dried negs.

Where the sediment was, there is no pyro stain (in a streaking pattern) but it's clear that the development happened.

Question 1)
So, I'm wondering if there's a way to do something with the negs so that this weirdness doesn't show in the print... e.g. remove stain and then re-stain.

Question 2)
I've never run into this problem before and my working method has stayed the same (efke 25 in PMK 1:2:100 @ 9.5 min. slosher tray agitation every 15 sec. 30 sec water stop. 5min fix. 2 min stain with agitation every 30 sec) though I did just buy new developer (PMK liquid from B+H)

I seem to remember reading something about bromides releasing when using pyro and causing uneven stain. Could this be the "sediment" I saw? Is there something else I should check?

Finally, the photo dept's tap water gets filtered before it comes out of the pipes and the filters were replaced at the beginning of the month. I'm not so sure the sediment is coming from the tap.




Gary Beasley
27-Oct-2007, 06:23
Sounds a bit like dichroic fog, which leaves a colored sludge on the surface of the film. I've heard that gently rubbing the sludge off while the film is still wet works. After it's dry possibly bleach and redevelop in fresh chemicals. I don't know what you will be able to do about the stain, I don't think that bleaches. I think an acid fix is supposed to fade stain. You might try that.

29-Oct-2007, 06:25

Jim Noel
29-Oct-2007, 14:51
sodium sulfite severely reduces stain prior to fixing. It would be worth a try on these negatives. SInce it is also a good hypo=clearing agent, nothing bad is gong to happen to the negatives by trying.

Doremus Scudder
30-Oct-2007, 03:14
Removing pyro stain can be done by using a sodium sulfite solution or an acidic solution. Normally, one would not want to remove the stain, since it would reduce contrast of the negative.

I have effectively removed pyro stain by trying to intensify a negative in selenium toner 1:2. The toned areas had no stain, similar to what you are describing.

For your case, I would first attempt to recover the stain by trying a couple of things. Note, I have never tried any of these, but they may work, and certainly will do little harm, especially to a damaged negative.

1: Try an alkaline bath, e.g. sodium metaborate or a carbonate solution and see if that helps. I believe Gordon Hutchins mentions this in his book on pyro.

2: Two to three minutes in spent developer. The alkaline environment and the presence of pyro might help. You also may get a bit of general staining though.

If none of the above helps, try an acidic bath to remove the stain. Stop might work, or, do what I inadvertently did, use Kodak Rapid Selenium Toner mixed 1:2. The toning will replace some of the lost stain density and possibly make the negative more printable.

Hope this helps. I'd love to hear your results. Please post them after you try some things.


Doremus Scudder

Gary Beasley
30-Oct-2007, 15:55
If you do remove the stain while doing the cleanup, bleaching with an oxidizing bleach then redeveloping in fresh pyro developer will restore the stain. This is supposed to be a good way to intensify a neg, using multiple bleach and develop cycles to build up the stain image. Simply putting the neg in spent developer is not recommended as it just builds up the base fog level of the stain and doesn't add anything to the image itself.