Questions about B&W film reversal

[Raghu Kuvempunagar]

fully developed a scrap if exposed film and bleached it as normal. After the 2 bleach steps and clearing bath, the film was still opaque and yellow, and when put in developer again it turns almost completely black. This is even after mixing up a bit of fresh bleach.

I believe you're talking about Copper bleach here. Looks like the first step (negative silver image to silver chloride) worked but the second one (clearing of silver chloride) didn't. Check your Ammonia. It needs to be at least 2% and reasonably fresh.

 

[MCB18]

I believe you're talking about Copper bleach here. Looks like the first step (negative silver image to silver chloride) worked but the second one (clearing of silver chloride) didn't. Check your Ammonia. It needs to be at least 2% and reasonably fresh.

Ferric chloride, actually. Not copper. And I used a bit of ammonia straight from the bottle, should be 10%, but might be a bit less now. Smelled fucking awful so I know it’s still good..

 

[koraks]

Ferric chloride, actually.

Try a more regular, dependable bleach.

 

[dcy]

Whoo hoo! Success!

I did the same bleach test as @MCB18 --- Fully exposed the film, develop, stop, bleach steps, and clearing bath. --- I have the ingredient to make all three bleaches, so I decided to use ferric chloride to match @MCB18. Because I was curious about the role of sodium sulfite, I did two tests:

Test 1: Bleach ---> Ammonia ---> Sulfite sequence (i.e. reverse sequence).

Test 2: Bleach ---> Sulfite ---> Ammonia sequence (i.e. "default" sequence).

Note that the video describing the variant with ferric chloride uses the reverse sequence, but it also uses sodium metabisulfite, and that might be an important difference. Without further ado, here are the results:

As you can see, the reverse sequence left a significant amount of stain, which was avoided with the "default" sequence. The intended purpose of the sulfite bath is to prevent staining. It appears that it is indeed an important step for the ferric chloride bleach.

I also noticed that the solid precipitates looked very different. When ammonia came first, the film formed some fairly large "flakes" of red material. I don't know what that is. Silver chloride should not be red. But when the sodium sulfite bath came first, the red material was a fine powder that drifted off into the liquid easily.

Here are close-ups of the results with the reverse sequence:

And here are close-ups of the results with the default sequence --- don't mind the mark on the film; I was just too aggressive with the tongs and scratched the film.

 

[dcy]

Ferric chloride, actually. Not copper. And I used a bit of ammonia straight from the bottle, should be 10%, but might be a bit less now. Smelled fucking awful so I know it’s still good..

Let's see if we can diagnose this. Today I tried the same test as you and I got good results. Let's see... this is what I did:

Exposure: I exposed the film to room lights and held the film close to a lightbulb.

1st Developer: Paper developer with a strong dilution (Eco Pro 1+4) for 10 full minutes.

I am 100% sure that this is way overkill, but I really wanted to make sure that 100% of the silver was developed. The easiest way for the test to fail is if the initial development is insufficient.\\

Stop Bath: 2 minutes.

Bleach: Ferric chloride with water in a 1+1 ratio for 5 minutes.

Sodium Sulfite Bath: 2 minutes. ---- Causes a red powdery substance. The liquid gets quite "dirty".

Ammonia Bath: 2 minutes. ---- This might have been the stage when the film turned transparent, but I'm not sure. I couldn't get a good look at the film when it was inside the sulfite bath.

Wash: 2 minutes under the faucet. I actually scrubbed the film with my (gloved) fingers.

2nd Developer: I just put the film back in the same developer for another 3 minutes.

Did not see any development at all. The film stayed just as clear as when it came out of the ammonia bath.

Stop Bath: 2 minutes.

Fixer: 2 minutes.



Do any of these steps look different from what you did?

 

[dcy]

Try a more regular, dependable bleach.

AFAIK the only beaches that fit that definition are the "classic" potassium dichromate or permanganate bleaches. The purpose of all the XXX-chloride bleaches is to pick something a little less harmful.

After the potassium dichromate and permanganate bleaches, the next most "regular" bleach uses sulfuric acid.

Beyond that, I think every bleach has had its share of reported failures. @relistan has had limited success with his efforts to make citric acid work.

 

[MCB18]

Let's see if we can diagnose this. Today I tried the same test as you and I got good results. Let's see... this is what I did:

Exposure: I exposed the film to room lights and held the film close to a lightbulb.

1st Developer: Paper developer with a strong dilution (Eco Pro 1+4) for 10 full minutes.

I am 100% sure that this is way overkill, but I really wanted to make sure that 100% of the silver was developed. The easiest way for the test to fail is if the initial development is insufficient.\\

Stop Bath: 2 minutes.

Bleach: Ferric chloride with water in a 1+1 ratio for 5 minutes.

Sodium Sulfite Bath: 2 minutes. ---- Causes a red powdery substance. The liquid gets quite "dirty".

Ammonia Bath: 2 minutes. ---- This might have been the stage when the film turned transparent, but I'm not sure. I couldn't get a good look at the film when it was inside the sulfite bath.

Wash: 2 minutes under the faucet. I actually scrubbed the film with my (gloved) fingers.

2nd Developer: I just put the film back in the same developer for another 3 minutes.

Did not see any development at all. The film stayed just as clear as when it came out of the ammonia bath.

Stop Bath: 2 minutes.

Fixer: 2 minutes.



Do any of these steps look different from what you did?

I have been doing the clearing bath after the ammonia. I also use Dektol 1+3 for about 3-4 minutes.

Are you guys doing all of this in room light by chance? I have been because I didn’t think it mattered for this test?

 

[koraks]

After the potassium dichromate and permanganate bleaches, the next most "regular" bleach uses sulfuric acid.

If you apply some sensible work practices, you end up with some chromium (III) or metallic manganese, neither of which are major concerns either way, and some sulfate. Not so pretty if you use kilos of the stuff, but the few grams you need to process a box of film...well. Let's not exaggerate. If you want to steer clear of the dichromate, which I can very well imagine, permanganate is in my view a perfectly reasonable alternative. It's sold to combat fungal infections in Koi fish and to disinfect water in survival situations, to name a few. Again, not nice if you dump a kilo into a nearby stream. In small amounts, just not much of a concern. I honestly don't see the problem with sulfuric acid if people use hydroxide to make their developer concentrate without batting an eye, or glacial acetic acid to mix a stop bath. Risk perception and management in home darkroom situations can be a really funny, irrational affair much of the time.