Black dots on negatives - phenidone?

[eumenius]

Hello friends,

here's an unpleasant thing I did observe recently: my negatives come out from HQ-Phenidone developers (homebrew Microphen and Diafine) with numerous tiny black dots here and there. The dots are not sharp, they look more like smudged falling snow - I suppose this is the diffusion tail. I've never had it before, but something tells me that it's the phenidone falling out of the developers. I tried to filter them through 1.2 micron filter - no way, right after filtration they get visibly opalescent. Maybe it was a bad idea to dissolve phenidone in isopropylic alcohol before adding it to developer? I am almost sure it is the source of problem, so I would make all the solutions fresh tomorrow, without isopropanole. What a pity! First time in my life!

Zhenya

 

[Ian Grant]

Definately not the Phenidone falling out of the developer, once in solution it does not drop out.

More likley bits of edge emulsion or another contaminant. Although I suppose its possible your phenidone/ alcohol mix didn't disperes prperly into solution.

Personally I've tried but never bothered again dissolving the Phenidone in an alcohol first. I've always found it dissolve quite easily, although pehaps not immediately.

 

[Bruce Osgood]

If you're using Photo-Flo as a wetting agent it probably is time to make new.

 

[Maine-iac]

Hello friends,

here's an unpleasant thing I did observe recently: my negatives come out from HQ-Phenidone developers (homebrew Microphen and Diafine) with numerous tiny black dots here and there. The dots are not sharp, they look more like smudged falling snow - I suppose this is the diffusion tail. I've never had it before, but something tells me that it's the phenidone falling out of the developers. I tried to filter them through 1.2 micron filter - no way, right after filtration they get visibly opalescent. Maybe it was a bad idea to dissolve phenidone in isopropylic alcohol before adding it to developer? I am almost sure it is the source of problem, so I would make all the solutions fresh tomorrow, without isopropanole. What a pity! First time in my life!

Zhenya

I use phenidone developers exclusively and always dissolve the phenidone in isopropyl alcohol and have never experienced this problem. Never heard of phenidone coming out of solution. Turn your focus elsewhere to some other part of your process-- water quality, fixer that has bits of silver in it, etc.

Larry

 

[rogueish]

What type of film are you using?

 

[eumenius]

Dear friends,
thank you for your hints! I am absolutely sure my Phenidone behaves wrong - the only component liable to precipitation in my developers is Phenidone, and the residue on 1.2 micron filter is seriously yellow... maybe after being poured in as a isopropanol solution it becomes something like a colloid solution, then aggregates back? The developers turn opalescent, then form precipitates, that's for sure, and filtration doesn't help. All other parts of my process work perfectly with Rodinal, so that's not a problem - I love to keep it all tidy I don't use Photo Flo - it's not sold here My primary film is Fomapan 100, but again, it gives no dots in Rodinal. I will make fresh developers today and see what happens. I use always a distilled water, so its quality is not a problem.

Regards,
Zhenya

 

[juan]

what is the dilution of the alcohol? Where I live, I can buy only 40% which does not seem to dissolve phenidone any better than plain water. Could it be that you did not mix the phenidone thoroughly - that might account for the yellow on the filter.
juan

 

[eumenius]

what is the dilution of the alcohol? Where I live, I can buy only 40% which does not seem to dissolve phenidone any better than plain water. Could it be that you did not mix the phenidone thoroughly - that might account for the yellow on the filter.
juan

Hi Juan,
the alcohol I use is 100% - you see, I'm a professional biochemist so I have a full access to chemistry. It dissolves phenidone pretty well, giving a true solution - when it's poured in the developer, it gives a clear solution first. The precipitation begins to occur on the next day, maybe. I mix an isopropanol-free version of Diafine solution A, so today I will have an answer

Zhenya

 

[Donald Miller]

Never had this problem from using phenidone in my film developer. I did have a problem like this when my film presoak solution had particles in it. I found that the particles adhered to the softened emulsion and then the film developer could not develop the film evenly.

 

[titrisol]

You are seeing a yellow precipitate, that makes me wonder whether it could be Sulphur (from the sulphite) or some yellow salt.
I'd test for the sulfur first.
Solubility of phenidone goes above what we use in photography, so it shouldn;t be a problem.

 

[gainer]

I don't use isopropanol anymore as solvent for phenidone. I like methanol better, and propylene glycol better yet. It takes a little heating to make a 1% solution in the glycol, but I think it keeps longer. I can't remember ever seeing phenidone precipitate out in my 30 or so years of using it, nor have I seen any of the black spots you describe. Is it possible that the concentration of phenidone in the A part is a little higher than it needs to be? The ratio of phenidone to the hydroquinone need not be any higher than 1 part to 40. Phenidone in water is not very soluble from what I read.

 

[titrisol]

I have always thought that 1% sols of phenidone were made to make it easier to use 0.01g fo phenidone (1ml solution) rather than requiring triple beam balances.

I don't use isopropanol anymore as solvent for phenidone. I like methanol better, and propylene glycol better yet. It takes a little heating to make a 1% solution in the glycol, but I think it keeps longer. I can't remember ever seeing phenidone precipitate out in my 30 or so years of using it, nor have I seen any of the black spots you describe. Is it possible that the concentration of phenidone in the A part is a little higher than it needs to be? The ratio of phenidone to the hydroquinone need not be any higher than 1 part to 40. Phenidone in water is not very soluble from what I read.