_tf_
5-Feb-2022, 09:17
About a month ago my PyrocatHD (1+1+100 @ 20C) developed negatives (Fomapan 100) started showing red-purplish stains. I am using the Stearman SP-445 tank, and the stains are on the non-emulsion side of the sheets at the locations where there is an open space in the film holders (i.e., where liquid gets potentially trapped between the two sheets), most pronounced at the top of tank and one side, but in some cases running the length of the hole in the holder, and at times also at other places where there is a void behind the sheet. The nature of the stains makes them difficult to capture on a photograph, but this scan makes it clear:
https://live.staticflickr.com/65535/51864154390_6c9f5b65e9_z.jpg (https://flic.kr/p/2n24mbs)Gundlach No. 2 Verastigmat lens test (https://flic.kr/p/2n24mbs) by tthef (https://www.flickr.com/photos/_tf_/), on Flickr
The pronounced bright spot in the top right is caused by the red stain on the back of the negative and corresponds to the location of the hole in the SP-445 holder; there is a less noticeable one to the left of that and another that is not visible on the scan further to the left, again corresponding with the other holes in the holder.
I have stumbled on this thread, that shows what I think is the same issue, but on 120 film, https://www.photrio.com/forum/threads/fomapan-100-what-gives.185354/#post-2442055, and the stain is very clear there, more so I could capture on my sheet film (mine is slightly more toward red in tone), but the thread did not come to any useful conclusion.
I am fairly certain it's not a problem with the film itself, I have developed quite a lot of Fomapan 100 in PyrocatHD without issues, some of it from the same box of film. I suspect this is something to do with the staining process of PyrocatHD and the fact there is a small volume of liquid trapped in these locations that I imagine is not much replenished during agitation. I wonder if anyone has any idea if something/what in the PyrocatHD chemistry could cause the stain going read-ish, particularly if this could be due to failure of solution B (I think I mentioned elsewhere on the forum the powder in the B bag appeared to be contaminated, and the solution was not clear to start with, and I think is getting darker; I am going to mix a fresh one, unfortunately I have also recently changed to using acetic acid for stop instead of ilfostop, and started using 1% sodium sulfite to speed up washing, and I can't remember if the stains first appeared before or after this change, so I have more variables to eliminate by simple trial and error.)
Also, I would be interested in any suggestions about what to try to remove the stain; it's on the surface of the substrate, and can be scraped off with a scalpel, but that damages the substrate too much to be practical. I have tried alcohol, nafta and gamsol, but none makes any effect. I now I have quite a few sheets to experiment with, and a couple I would love to be able to fix (I initially thought these were finger prints, so first went for more hand washing and then using gloves to handle the sheets ... :( ).
https://live.staticflickr.com/65535/51864154390_6c9f5b65e9_z.jpg (https://flic.kr/p/2n24mbs)Gundlach No. 2 Verastigmat lens test (https://flic.kr/p/2n24mbs) by tthef (https://www.flickr.com/photos/_tf_/), on Flickr
The pronounced bright spot in the top right is caused by the red stain on the back of the negative and corresponds to the location of the hole in the SP-445 holder; there is a less noticeable one to the left of that and another that is not visible on the scan further to the left, again corresponding with the other holes in the holder.
I have stumbled on this thread, that shows what I think is the same issue, but on 120 film, https://www.photrio.com/forum/threads/fomapan-100-what-gives.185354/#post-2442055, and the stain is very clear there, more so I could capture on my sheet film (mine is slightly more toward red in tone), but the thread did not come to any useful conclusion.
I am fairly certain it's not a problem with the film itself, I have developed quite a lot of Fomapan 100 in PyrocatHD without issues, some of it from the same box of film. I suspect this is something to do with the staining process of PyrocatHD and the fact there is a small volume of liquid trapped in these locations that I imagine is not much replenished during agitation. I wonder if anyone has any idea if something/what in the PyrocatHD chemistry could cause the stain going read-ish, particularly if this could be due to failure of solution B (I think I mentioned elsewhere on the forum the powder in the B bag appeared to be contaminated, and the solution was not clear to start with, and I think is getting darker; I am going to mix a fresh one, unfortunately I have also recently changed to using acetic acid for stop instead of ilfostop, and started using 1% sodium sulfite to speed up washing, and I can't remember if the stains first appeared before or after this change, so I have more variables to eliminate by simple trial and error.)
Also, I would be interested in any suggestions about what to try to remove the stain; it's on the surface of the substrate, and can be scraped off with a scalpel, but that damages the substrate too much to be practical. I have tried alcohol, nafta and gamsol, but none makes any effect. I now I have quite a few sheets to experiment with, and a couple I would love to be able to fix (I initially thought these were finger prints, so first went for more hand washing and then using gloves to handle the sheets ... :( ).