Standardizing B&W reversal process for an experiment on FD composition

So I'm preparing to go ahead with testing some different B&W reversal first developer formulations. In order to control as many variables as I can, I'd like to run all the films through the exact same process so that the differences seen can be attributed to the first developer formulation.

I'd like to solicit your help, and verify that I haven't made any really poor decisions. Please read my planned process and advise me if I've made any blatant errors or if you see any parts you think could be improved.

Process	Solution	Time	Rationale
Pre-rinse	Water	1 minute	Eliminates possibility of air bells, swells gelatin evenly to allow for developer to enter at a constant rate.
Variable First Developer
Stop	Ilfostop	30 seconds	Despite the beneficial edge effects described in Haist using a water rinse instead of stop bath, a stop bath was chosen for consistency of development time.
Rinse	Water	fill, invert 5 times, dump, repeat 10 times.	Avoids interaction between FD and bleach which can result in chromic sludge being deposited onto the film, tank, and reels
Bleach	Kodak R9 (substituting out conc. sulfuric acid): 66g/L sodium bisulfate + 9.5g/L dichromate	5 minutes	Permanganate is not recommended with SCN for some reason. Additionally dichromate bleaches soften gelatin less than permanganate bleaches. Sodium bisulfate used as sulfuric acid could not be obtained.
Rinse	Water	fill, invert 5 times, dump, repeat 3 times.	Lengthens the active life of the clearing bath.
Clear	Kodak CB-3: sodium sulphite (anhy) 10g/L	1 minute	Removes the oxidation products of dichromate bleaching. Restores light sensitivity lost by bleaching. The dilute CB-3 minimizes the solubilizing effect of sulphite on AgX.
Rinse	Water	fill, invert 5 times, dump, repeat 10 times.	Removes the sulphite so as to minimize its solubilizing effect on AgX
Rexpose to light	800fc-sec	1 minute at 3 feet distance from a 1490 lumen incandescent light bulb.	Fogs the AgX so as to render it developable while avoiding excessive exposure which may cause solarization and fogging of less sensitive grains which would increase Dmin.
Second Developer	D72/Dektol (1+3)	4 minutes	Out of D-8, D-19 and D-72, D-72 was chosen as it contains the lowest amount of sulfite, which can solubilize AgX.
Stop	Ilfostop	30 seconds	This stop is only to help wash out metol from the film to help preserve the fixer which I will use for processing B&W negatives and paper as well as for reversal processing.
Rinse	Water	fill, invert 5 times, dump, repeat 3 times.	Helps to wash out developer and stop bath, lengthening life of the alkaline fixer.
Fix	TF4	3 minutes	Removes any highly insensitive AgX grains that would only increase Dmin if they were developed, toned, or printed out.
Wash	Running water	25 minutes	Washes out thiosulphates for long term stability.

I have not much experience with B&W reversal, but have done many tests and experiments with color reversal. With two developers used in two separate steps there are things which can go wrong in one and work out thanks to the other one anyway. While e.g. Fuji and Kodak E6 chemistry will give you very similar overall results, it is not recommended to e.g. use Kodak FD and Fuji CD.

Since you want to only look at first developer step, make sure that the rest of the process chain more or less what you want to use later on. This applies specifically to stop bath, bleach, reexposure and second developer.

Back when Kodak made a B&W reversal kit the clearing agent supplied for the first developer was 2-thiobarbituric acid. It was chosen because it produces clearer highlights with fewer problems. BTW unsubstituted barbituric acids have no drug uses. IIRC the amount used per liter of developer was 1 g or less.

Alessandro Serrao said:

Afaik Kodak Used D-TOD in the first developer.

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D-TOD? I know I am going feel dumb but the abbreviation escapes me today.

Alessandro Serrao said:

Dithiaoctane diol

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Thanks. I remember buying the thiobarbituric acid. I still have the bottle somewhere. My point was that thiocyanate and thiosulfate need not be used there are better clearing agents.

Thanks so much for the input. Does anyone have some literature on thiobarbituric acid or Dithiaoctane diol as clearing agents in reversal first developers? I am really interested in this. I've never heard of them before. I decided to go with thiocyanate since it is recommended in Haist over thiosulfate. I kind of understand the theory too, since the silver-thiocyanate complex is weaker than silver-thiosulfate complexes, which allows for a faster physical development rate. As I understand it, the goal of the reversal FD is to balance physical and chemical development so as to get clear highlights and good Dmax. I might try with some high sulfite developers too just to see if that could be workable.

Gerald C Koch said:

My point was that thiocyanate and thiosulfate need not be used there are better clearing agents.

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I've been mostly unsuccessful in my search for information about better clearing agents than thiosulfate and thiocyanate.

(there was a url link here which no longer exists) that DTOD holds no advantage over thiosulfate in terms of image quality. (there was a url link here which no longer exists), thiosulfate was used in old formulae, and not much past the 1940's excepting Ilford's most recent recommendation. It seems as though the major shortcomings of thiosulfate are its instability in developer solutions and its tendency to form dichroic fog.

Thiocyanate is (there was a url link here which no longer exists) than thiosulfate, but there is (there was a url link here which no longer exists) by the strong oxidizing bleach if an adequate stop and wash is not used between the FD and bleach. For some reason that is not clear to me, this seems to be more of a problem with permanganate than dichromate, since thiocyanate is not recommended when a MnO4 bleach is used, but there is no such recommendation for Cr2O7. However, the change from thiocyanate to DTOD was (there was a url link here which no longer exists) from dichromate to permanganate. In an E6 colour developer, (there was a url link here which no longer exists) that DTOD is much superior than thiocyanate, but I don't know why that is, or if it has any bearing on a b&w FD.

If anyone has any information or can refer me to some info either here on APUG or elsewhere regarding first developer clearing agents, I'd be very appreciative.

AFAIK most E6 FD formulas use Thiocyanate, not DTOD. Interestingly, E6 CD seems to use DTOD, so we can assume that DTOD was known and understood by the time E6 was created, and that E6 FD's use of Thiocyanate must have a reason.

While Thiocyanate may create poisonous gas in conjunction with strong oxidizers, one should not create unnecessary hysteria over it. There isn't all that much Thiocyanate in reversal FD to begin with, and with two or three wash cycles after FD there should be extremely little left. Since the bleach is fairly dilute, we don't want to bring in carry over FD anyway, so I consider wash between FD and bleach a given. Given all that, plus the high toxicity of Dichromate, I feel safer using FD with Thiocyanate + wash + Permanganate bleach than the same FD with Dichromate bleach.