Permanganate reversal baths

[Helen B]

Here's Kodak FD-72

Part - A
Sodium Dithionite: 5.0 grams

Part - B
Water: 900 ml
'Kodalk' Balanced Alkali or sodium metaborate tetrahydrate: 10.0 grams
EASTMAN L-(+)Cysteine Hydrochloride: 0.3 gram
Add water to make 1 litre

Use: Dissolve 5 grams of Part A in 1 litre of Part B just before use - it only has a life of about 2 hours after mixing.

Best,
Helen

 

[Jordan]

Re-exposure and re-development certainly work. The problem I had when I tried it was that I went overboard -- I actually 'solarized' the film. With greater control I'm sure it would work well. I just went with the thiocarbamide method to avoid the solarisation, and I find the tone very pleasing with Pan F Plus.

Helen's formula is interesting. Cysteine was probably used because it is an inexpensive thiol source. Thiobarbituric acid is probably not controlled and is probably just like thiourea. I bet that a trace of thiourea would work just as well. Note that the concentrations are low in these formulae.

 

[gainer]

This was a sad day for me. I made a mistake.

When I tested Super Iron Out I did not re-read the fine print. It contains sodium bisulfite in addition to the sodium dithionate. It's a wonder it blackened exposed film. I thought I remembered that it had sodium carbonate. Nope.

I did another Q&D experiment, adding 1 tsp Super Iron Out and 15 ml of a 50% NaOH (by weight) solution I had on hand to 250 ml water. It blackened a piece of unexposed HP5+ in about 2 minutes in the dark.

I suspect that a solution of Iron Out alone would keep pretty well.

The 50% solution by weight is 100 grams of NaOH in 100 ml water. It's handy to have on hand. If nothing else, you can use it to clear clogged drains.

 

[gainer]

P.S.
If you get the idea to use ready-mixed drain cleaner in place of the NaOH, be sure it does not contain a hypochlorite. That stuff will dissolve the emulsion. I found that out one day as a result of my other mistake.

 

[Helen B]

I'll definitely be trying Patrick's method as soon as I have the chance. Thanks for that.

It looks like 10 g/l iron (II) sulphate 7-hydrate with 15 g/l potassium fluoride can be used as a fogging agent. Instead of the fluoride you can use 10 g/l citric acid or 1 g/l conc. sulphuric acid.

Best,
Helen

 

[rjr]

Jordan,

prices depend on the retailer - the price for tin-II-chloride is outrageous at mine, but dithionite and thiorea cost exactly the same.

I have sodium dithionite at my place, using it to de-silver my spent fixer.

In doses of 500g I pay 7 or 8EUR per pack.

Side story - I am just returning from Photokina and spoke with the Foma guys. They will look into making Fomapan R100 in rollfilm and I showed them a bad mistake in their german instruction sheet. It said to prepare 30ml of sulphuric acid, add 270ml of water to it... no, not a good idea, is it?
One guy went to the back room and pulled out a box of their reversal kit, I showed it to them in print. Once they realised what I was talking about the man stuffed the instruction sheet, closed the box...
...
and handed it over the counter. "For you. THANKS a lot, that could have ended up bad!". Well, I had to carry it all day, but... nice. ;-)

 

[gainer]

I'm surprised you guys didn't jump at the opening I left by implying that I have only made 2 mistakes.

 

[waterpump]

Just stumbled on this thread from some years ago. I'm currently doing 16mm film black and white reversal with dichromate bleach. However, might be worth pursuing acid thiourea as a silver bleach? Alternatively permanganate with an acid buffer system to control the pH (degree of acidity) and hence 'aggressiveness' of the bleach? I'll try and look into this. Great thread!

 

[waterpump]

Did you ever try this. Alkaline Sodium Dithionite can also be used as a fogging agent.

 

[waterpump]

It looks like 10 g/l iron (II) sulphate 7-hydrate with 15 g/l potassium fluoride can be used as a fogging agent. Instead of the fluoride you can use 10 g/l citric acid or 1 g/l conc. sulphuric acid.

Best,
Helen

Did you ever try this? Fe++ ferrous salts are developers in weakly alkaline solutions, but unstable, needs organic acids / ammonia to stabilise...
Alkaline Sodium Dithionite can also be used as a fogging agent.