A really wild guess. Could it be that your Foma 100R slides were not sufficiently fixed and hence had some halides (perhaps iodides) which got developed when you redeveloped the slides after bleaching?
Fomapan R 100 reversal with D19 anyone?
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A really wild guess. Could it be that your Foma 100R slides were not sufficiently fixed and hence had some halides (perhaps iodides) which got developed when you redeveloped the slides after bleaching?
OP
OP
After FD and SD? A bit hard IMHO.
I keep thinking it's a problem of silver halide solvent in fd, since the leader is coming crystal clear it can't be a bleach problem.
I have a 30metre roll of R100. Without reading the whole thread, is there a recommended home developer?
Yes, that is the Foma R100 kit. Faboulous and perfect results, consistent every time.
You can buy it from Foma.cz online shop, it's even cheaper that way.
Thank you. Does the process involve exposure to light, or is achieved chemically as with some E6 processes?
light
OP
OP
A small, belated update...
It's been a while since I processed another R100 film, this time at EI125 and with 10% decreased time in FD (D19 stock). This time I also made another change, using sulfuric acid instead of bisulfate for the permanganate bleach. The slides are projection worthy and do look good, but the only thing that bugs me is minimum density. It's much better than the previous try, but there's a bit density that I'd like to get rid of.
Another uncertainty I hadn't addressed was the hydration state of my sodium carbonate, which was supposedly anhydrous. I baked it in the oven and it turns out that it had 9% water, making it a mixture of anhydrous and monohydrate. This is not exactly insignificant, but I don't really know how big of a difference it can make when mixing D19.
Finally, I confirmed that my bisulfate had a halide impurity. It occurred to me that my HT-2 test solution, which is basically silver nitrate, could be used to check for halides. Sure enough, my tap water becomes cloudy when I add some drops of the silver nitrate solution. A solution of my sodium bisulfate in deionised water also did so, although not as badly. My sulfuric acid didn't produce any cloudiness, nor my sodium hexametaphosphate. My potassium permanganate is tougher to assess, because the solution becomes coloured even with a tiny amount of permanganate, but it didn't seem to produce anything.
This halide impurity of my bisulfate can explain the increased minimum density with R100, but the same bleach didn't behave so with Rollei Retro 80S, where it gave perfectly clear film. Does anyone have a plausible explanation?
Anyway, I'd like to do some more testing, perhaps at EI 160 with the initial FD time of 10'. Combined with the sulfuric acid bleach, it might give a clear film leader.
It's been a while since I processed another R100 film, this time at EI125 and with 10% decreased time in FD (D19 stock). This time I also made another change, using sulfuric acid instead of bisulfate for the permanganate bleach. The slides are projection worthy and do look good, but the only thing that bugs me is minimum density. It's much better than the previous try, but there's a bit density that I'd like to get rid of.
Another uncertainty I hadn't addressed was the hydration state of my sodium carbonate, which was supposedly anhydrous. I baked it in the oven and it turns out that it had 9% water, making it a mixture of anhydrous and monohydrate. This is not exactly insignificant, but I don't really know how big of a difference it can make when mixing D19.
Finally, I confirmed that my bisulfate had a halide impurity. It occurred to me that my HT-2 test solution, which is basically silver nitrate, could be used to check for halides. Sure enough, my tap water becomes cloudy when I add some drops of the silver nitrate solution. A solution of my sodium bisulfate in deionised water also did so, although not as badly. My sulfuric acid didn't produce any cloudiness, nor my sodium hexametaphosphate. My potassium permanganate is tougher to assess, because the solution becomes coloured even with a tiny amount of permanganate, but it didn't seem to produce anything.
This halide impurity of my bisulfate can explain the increased minimum density with R100, but the same bleach didn't behave so with Rollei Retro 80S, where it gave perfectly clear film. Does anyone have a plausible explanation?
Anyway, I'd like to do some more testing, perhaps at EI 160 with the initial FD time of 10'. Combined with the sulfuric acid bleach, it might give a clear film leader.
That suggests there's still a bit of undeveloped silver if you're getting a Dmin that's higher than you'd like?
OP
OP
Yes, that's a possibility I want to explore. That's why I'd like to try 10' in FD at EI160. EI100 is overexposed.
I think a 2/3-1 stop shadow speed boost seems fairly normal for reversal development - nevertheless, you'd normally have to increase exposure to resolve the Dmin issue (by exposing the silver halide) - unless you want to try a tiny amount of silver solvent or an accelerator?
OP
OP
Fomapan R100 doesn't have a very high Dmax, so adding a silver solvent will probably weaken it too much. I don't have any accelerator at hand, so that's not an option. BTW, EI160 is what Dr5 suggests for this film and he doesn't use a silver solvent in his FD AFAIK.
I don't have an explanation exactly, but Fomapan R100 behaved totally differently than other films in the peroxide bleach, induced in part by the silver-based antihalation layer. Could the bleach have exhausted from the amount of silver dissolved, or just been slower and needed more time as a result?
D-19 (and the D-11 that DR5 claims to make a good FD) both have enough sulphite to be considered at least somewhat solvent - but I do wonder about how much overall fog they generate vis-a-vis actually developing all the silver. I do note that Fomadon LQR (the FD in Foma's developing kit) uses Trisodium Nitrilotriacetate, which could be playing a role similar to what Ron outlines in the second line in this post here - chelated ferric ions oxidise metallic silver into soluble silver ions.
You can use tiny amount of thiocyanate (< 0.25g/l) in FD to clear the highlights without losing DMax in the present case. It takes substantially more thiocyanate to deplete the halides in the shadow areas.
It could be the Carey-Lea colloidal silver in the AHU layer of Fomapan 100-R that's more susceptible to rehalogenation by the halide impurities in the bleach. Some of the silver in Carey-Lea layer could be charged making it easier to rehalogenate.
OP
OP
It's not exhausted, but needs quite a lot of time. 8' is what Foma suggests in permanganate bleach and this seems to work. A weaker bleach would have a hard time bleaching it. I've done the full process in a graduate in full room light, half of the film was covered with selotape, which was removed after the first wash. The film looked clear after the clearing bath. After being redeveloped and fixed, it seems to be a little denser. It is either a little bit of rehalogenation taking place, or the highlights not being as clear as I think they are after the clearing bath. If rehalogenation takes place, it is to a far lower extent compared to my bisulfate bleach.
OP
OP
Who knows, it might actually be plausible, considering that these two films have this silver layer as their most significant difference.
OP
OP
Hello Raghu, it's been quite a while...
I tried another Fomapan R 100 today, it's hanging to dry now. I used a ~2% ammonia bath after the clearing bath this time, for 2'. I combined the reexposure and the ammonia bath in a single step and cut a bit of processing time this way. Anyway, it seems that it did the trick and the leader looks clearer. I shot it at EI160 and it looks nice. I might be able to post examples tomorrow, perhaps even a characteristic curve.
PS No signs of emulsion damage from the ammonia bath. At this point, I'm genuinely puzzled about how the permanganate bleach got such a bad reputation. It may soften the emulsion quite a bit and make it much more easy to scratch, but I've never seen it lifting off the base like some have reported.
I'm glad it worked well. Thanks for sharing the experience. Will look forward to seeing the pics and the curve.
OP
OP
Ok, before saying anything else, I have to point out that I don't own a densitometer, but use a Minolta Scan Dual III scanner as a densitometer. The readings from high density areas are iffy, but low densities must be pretty accurate. So, I checked the leader of the film and it seems to have a density of about 0,05 or so. Worst case would be 0,1 I suppose. In any case, it's clear enough and whatever problems I had in the past are not evident in this film. Another observation is that it's a long toe film, at least when processed in D19. I bracketed a gray card and at +3 stops it's nowhere near pure white. At -3 it's quite close to Dmax. I'll post samples later
OP
OP
Ah, the scans...
Even though this film isn't terribly dense, my scanner seems to have a hard time making good scans. The shadow areas when elevated to normal brightness have quite a bit of noise. And then there are also other problems that aren't present in the film, like halo around highlights and overall low sharpness. The low sharpness might be related to poor focus in the scanner. They look very nice and sharp when viewed with a loupe, but the scans don't do them justice. But anyway, here's a sample from the latest film:
And here's another from the previous attempt:
Even though this film isn't terribly dense, my scanner seems to have a hard time making good scans. The shadow areas when elevated to normal brightness have quite a bit of noise. And then there are also other problems that aren't present in the film, like halo around highlights and overall low sharpness. The low sharpness might be related to poor focus in the scanner. They look very nice and sharp when viewed with a loupe, but the scans don't do them justice. But anyway, here's a sample from the latest film:
And here's another from the previous attempt:
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