Yellow Staining on Negatives, Please Help

[G Benaim]

Hi everyone,

I've recently started getting this uneven yellow staining on my 7x17 negatives, with different films. Something is obviously going wrong somewhere but I can't figure this one out. One thing I should mention is I use the exact same regime with my 8x10 negs and havent seen any staining fwiw. I process in trays as follows: 3 minute presoak in plain water, development in Rodinal 1:50, 30 sec rinse in plain water, sodium thiosulfate fixer (i.e. plain hypo), permawash, etc. The staining is evident as soon as I turn on the lights. I've read that this might be dichroic fog from developer carrying over into the fixer, does that make sense? If so, will using an acidic stop instead of plain water help here? Is there any way to get rid of it? Will it show up in printing (given that it's yellow)? Thanks, here's one recent neg:

[Fred L]

I wanna say insufficient fixing, but guessing you have your process down pat. maybe a bit longer rinse in the water stop, or use proper stop or citric acid ? have you tried refixing ?

fwiw, I've never had these type of yellow stains with sheet film (4x5 to 7x17), and I also use water stop. hope someone can point you in the right direction.

[G Benaim]

Hi Fred,

I have tried refixing but it didn't help. I've gotten them with fresh fixer as well, so not sure what may be causing this. I'll try the acid stop just to rule that out. Is there any way to get rid of the stains? I read somewhere that farmers reducer can work. Also, will the stain show up on graded papers if it's yellow?

[interneg]

I'd start by using acid stop and rapid fix (as you should with modern films) & see if that clears up the issue - you have 50% more surface area for oxidation etc to happen on a 7x17 compared to an 8x10.

[Ken Lee]

You might try reducing some of the variables to help identify the cause, as follows:

1) Clean your hands and fingers with soap and water, then rubbing alcohol, then dry with a clean towel before all loading, unloading and processing. If the stains are consistently absent from the middle of the film, perhaps your skin is transferring something from any of the countless household products we regularly touch.

2) Use distilled water throughout the process. Not just the water for soaking, but the chemistry you mix. Eliminate any source of chemical contamination. So-called plain water can be anything but plain, and can vary over time. Back in the day, photo labs had elaborate filters to remove content from plain water.

3) Make sure all trays, tanks, etc. are completely clean. You many need to replace them.

4) Process two completely unexposed negatives. This should rule out the camera and holders. The negatives should be uniformly clear. If stains are identical on each sheet, then the film may be defective.

5) Check and clean your film holders, dark slides, etc. Perhaps all the defective negatives are from the same holder.

6) Check and vacuum the inside of your camera.

[G Benaim]

Problem solved, I could kick myself! I used an acid stop bath and no more spots at all, I guess the water bath wasn't doing the job properly. Now what to do about the stained negs. Has anyone ever used farmers reducer to remove dichroic fog? Any success stories or their opposite? What should I be wary of? Thanks.