Emulsion washed off film during reversal process

thefizz · Mar 31, 2014

I was developing a roll of Agfa Copex Rapid 120 in Foma's Reversal kit and following the second development stage the emulsion started to wash off the film during the rinse before fixing. The film looked fine when I opened the tank for the re-exposure and my temperature was accurate for all stages.

I never had this problem before. Any ideas why this has happened?

Peter

Rudeofus · Mar 31, 2014

The reversal bleach in that Foma kit contains Potassium Permanganate and Sulfuric Acid, both of which are pretty aggressive. Chances are they destroyed your emulsion, which then came off in the alkaline second developer.

Conclusion: either you made an error when you mixed your reversal bleach, or Agfa Copex Rapid 120 is not compatible with the Foma B&W reversal kit.

thefizz · Mar 31, 2014

I'm pretty sure everything was correctly mixed but I'll try another roll and see what happens. I understand Agfa Copex Rapid can be processed in the Agfa Scalla chemistry but maybe that is very different to the Foma kit?

Gerald C Koch · Mar 31, 2014

Permanganate and copper bleaches are both known to soften emulsions. A dichromate bleach is a better choice. Considering the thinness of microfilm emulsions I wonder if it is possible to get a satisfactory Dmax for positives.

pentaxuser · Mar 31, 2014

Can't help Peter as I have never tried Reversal processing. I can say that you should not beat yourself up on the grounds of incompetence if that helps. In our one meeting at Ilford and from your posts and experience I'd say you are very "switched-on" and do know what you are doing.

I am sure you will get it right. Nil desperandum

pentaxuser

MattKing · Mar 31, 2014

Any chance that the problem arises because of the film base used for Agfa Copex Rapid 120?

Athiril · Mar 31, 2014

I've had nothing but trouble with permanganate bleaches. Not worth it imho. I've had nothing but success with dichromate bleaches.

Xmas · Mar 31, 2014

most of my emulsion damage occurs with PET based film.

thefizz · Apr 1, 2014

So if I was to substitute the permanganate for dichromate, what dilution should I use and should mix it with the sulphuric acid in the Foma kit or with something else?

Athiril · Apr 1, 2014

thefizz said:
So if I was to substitute the permanganate for dichromate, what dilution should I use and should mix it with the sulphuric acid in the Foma kit or with something else?

I'll give some details when I get home, you don't need much sulphuric acid at all (or dichromate). Last I mixed mine I just eye balled it from experience.

Rudeofus · Apr 1, 2014

The biggest problem with Dichromate bleaches is that Potassium Dichromate is toxic and confirmed as a carcinogen for humans, and that's why most commercial kits will use Permanganate instead. Even if you manage to mix the Dichromate bleach without breathing in vapors or dust, there is a chance that you will spill little droplets during processing, which will again release dust once they are dry.

Sadly you can not use any of the bleaches commonly used in color processing either. If you are absolutely determined that you want to do this with Agfa Copex Rapid and Dichromate bleach, be prepared to provide all the required safety measures.

thefizz · Apr 1, 2014

What about Fotospeed's Chromium Intensifier? It is made up of Potassium Dichromate and Hydrochloric Acid. Could that be used?

Rudeofus · Apr 1, 2014

thefizz said:
What about Fotospeed's Chromium Intensifier? It is made up of Potassium Dichromate and Hydrochloric Acid. Could that be used?

You must not have an ion in your bleach that can form an insoluble Silver salt, and that Hydrochloric Acid would do just that. You can check whether this kit is shipped as one bottle, or with the Dichromate and the Hydrochloric Acid in separate containers.

thefizz · Apr 1, 2014

Rudeofus said:
You must not have an ion in your bleach that can form an insoluble Silver salt, and that Hydrochloric Acid would do just that. You can check whether this kit is shipped as one bottle, or with the Dichromate and the Hydrochloric Acid in separate containers.

Shipped in one bottle unfortunately but I can get Potassium Dichromate from my chemical supplier.

railwayman3 · Apr 1, 2014

I've used the Foma kit (permanganate bleach) successfully, but only with the recommended Foma film. I wonder if the microfilm emulsion is thin or less well hardened, not being designed for reversal.
However, many years ago I tried to process some "found" Dufaycolor film (basically a B&W reversal emulsion) using chemicals prepared to the official formulae. This had a permanganate/sulphuric acid bleach and the first attempt stripped the emulsion! I used a shorter bleach time for the remaining films with no problems, and the slides were actually quite successsful for film which must have been 30+ years outdated at the time.

Athiril · Apr 1, 2014

thefizz said:
What about Fotospeed's Chromium Intensifier? It is made up of Potassium Dichromate and Hydrochloric Acid. Could that be used?

That makes a rehalogenating bleach, which is the wrong type of bleach.

In my dichromate bleach, I used ~5mL of 98% sulphuric acid per litre of working bleach.

Kodak R21a Bleach Bath

Water 750ml
Potassium Dichromate 50g
Sulphuric acid (conc) 50ml
Water to 1 litre

Use 1:9

So 5g and 5mL in a litre of working solution, I've reused mine several times, works fine, insoluble stuffs builds up in it, but I filter it out.

Possible source:
http://www.goldenpages.ie/shaw-scientific-ltd-dublin-D12/2/

thefizz · Apr 2, 2014

Athiril said:
That makes a rehalogenating bleach, which is the wrong type of bleach.

In my dichromate bleach, I used ~5mL of 98% sulphuric acid per litre of working bleach.

Kodak R21a Bleach Bath

Water 750ml
Potassium Dichromate 50g
Sulphuric acid (conc) 50ml
Water to 1 litre

Use 1:9

So 5g and 5mL in a litre of working solution, I've reused mine several times, works fine, insoluble stuffs builds up in it, but I filter it out.

Possible source:
http://www.goldenpages.ie/shaw-scientific-ltd-dublin-D12/2/

Thanks for the information, I have sulphuric acid in stock so will get some potassium dichromate next time I'm ordering chemicals.

Xmas · Apr 2, 2014

railwayman3 said:
I've used the Foma kit (permanganate bleach) successfully, but only with the recommended Foma film. I wonder if the microfilm emulsion is thin or less well hardened, not being designed for reversal.
However, many years ago I tried to process some "found" Dufaycolor film (basically a B&W reversal emulsion) using chemicals prepared to the official formulae. This had a permanganate/sulphuric acid bleach and the first attempt stripped the emulsion! I used a shorter bleach time for the remaining films with no problems, and the slides were actually quite successsful for film which must have been 30+ years outdated at the time.

It may be the combination with a PET base - the base is dimensionally stable so if the emulsion shrinks or expands...

I get emulsion damage with PET base film mainly rebate abrasions loading plastic spirals cause I temper and minimise swelling to try and avoid any other stresses

Gerald C Koch · Apr 2, 2014

Dichromates are safe to use when treated with care and with proper safety equipment such as a dust mask, goggles, and gloves.

avortex · Apr 15, 2014

Dichromate is more dangerous in powder form (very volatile).
I usually have a bottle of 5 liters with twice the quantity of Potassium Dichromate diluted, and another one also with twice the quantity of sulfuric acid mixed.
When I want to process film, I just mix 50% of each one in the quantity I need, greatly minimizing my exposure to those dangerous chemicals.

Dichromate bleach is also very reusable. And remember to mix it with the clearing bath before getting rid of it. This way you can neutralize it...

Gerald C Koch · Apr 15, 2014

avortex said:
Dichromate is more dangerous in powder form (very volatile),

More dangerous yes but please it is NOT VOLATILE under normal conditions. Gasoline is volatile not inorganic salts.

avortex · Apr 16, 2014

You're right, Gerald. I used the wrong words!

mug · Aug 4, 2017

Hello Peter,
I just started with b&W reversal development. First rol an ∆100 was an good start. So I wan't to do better an bought film that seems better for slides (can't buy Agfa Scala anymore) and bought Agfa Copex also. Now I get same problem. All my emulsion is washed away in the 2e development. Cry,Cry snif, snif . . .
Did you ever find an solution te the problem ?
I use the Ilford manual and permanganate bleach. Does the Potassium Dichromate bleach give better results ?

Gerald C Koch · Aug 4, 2017

If you use Ilford's method using permanganate and stick to the formulas and recommended times and temperature you should be OK. This caveat applies to ALL solutions used in the process. Make no substitutions. Film manufacturers intend for their films to be processed normally and so they may not be hardened enough for reversal. Either switch to another film or use the dichromate bleach.

thefizz · Aug 4, 2017

Gerald C Koch said:
If you use Ilford's method using permanganate and stick to the formulas and recommended times and temperature you should be OK. This caveat applies to ALL solutions used in the process. Make no substitutions. Film manufacturers intend for their films to be processed normally and so they may not be hardened enough for reversal. Either switch to another film or use the dichromate bleach.

I gave up on permanganate bleach. It worked ok on some films but not on others. I switched to dichromate and have had no problems.

Emulsion washed off film during reversal process

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