Black precipitate in film developing tank after development [solved]

Today, for the first time, I found black stuff in my development tank after developing film. I've no clue what this could be. I'm going to filter it through a coffee filter later and dry it, maybe I can make out what it is. I've been doing the same process for over 20 years and never had something like it. That being said, there was one alteration today: the use of acid stop bath for 30s (citric acid) instead of two water exchanges.

I'm suspecting something, but I'm not sure... could the acid (or the developer) have dissolved the plastic of the Kindermann tank cap and the particles were trapped in the tank? The tanks are not the youngest, but I never had a problem and the caps look fine visually. The fixer is clear and the discarded wash water was inconspicuous too, the particles are in the tank only and i've discovered them after taking out the spools.

The film looks good on first sight. Hope it is ok and there are no spots or something.

Anyone seen a thing like this?

Oh yes: I'm using distilled water for the developer, fixer, and photoflo working solutions. Used tap water and 2 TSP citric acid for the stop (1L). I doubt its something in the water. Developer Rodinal, neutral/slighty acid fix. Ilfrod fill&dump wash. Kindermann SS 1L tank with plastic caps and SS reels. The film was Neopan 400 135. I filled/dumped the tank in daylight through the cap (except for photoflo which I did in a separate beaker)

Cheerio,
Andi

The acid is no where near strong enough to do damage to a developing tank. If you have not used a stop bath before, there may be a build up of converted silver i.e. the black precipitate loosened off the tank surfaces and that is what you are seeing.

I have had the same thing happen with a NOVA deeptank used for colour printing. The previous owner did not use a stop bath just a quick dip and dunk in plain water. When I first used it with stop bath the mess on the surface of the print had to be seen to be believed. Luckily it all lifted off when I washed the prints and there was no damage to them

Interesting. That would make sense though. Glad you could save your prints. I hope my film will be OK too.

I'm wondering how that much silver could attach to the tank. I put them into the dish washer once in a while and thoroughly washe the tanks after each use. Using the Ilford wash (dump and refill) method as well, so there's plenty of washing going on after the fixing.

How can I test if its really silver? Put some ST-1 on it an look for stain? Oh wait, you said "converted silver"...

Andi

~andi said:

Interesting. That would make sense though. Glad you could save your prints. I hope my film will be OK too.

I'm wondering how that much silver could attach to the tank. I put them into the dish washer once in a while and thoroughly washe the tanks after each use. Using the Ilford wash (dump and refill) method as well, so there's plenty of washing going on after the fixing.

How can I test if its really silver? Put some ST-1 on it an look for stain? Oh wait, you said "converted silver"...

Andi

Click to expand...

Could it be flaked-off AHL?

Hmm... I got some on my fingers when unspooling the film and it was kind of smeary. So why not. But how could this happen? I thought the AHL is designed to dissolve in water right? Rodinal usually takes care of that and comes out deep purple. The Neopan was outdated, but Dec 2015 isn't that long and I've developed at least 10 rolls of the same batch without black stuff.

I've run it through a coffee filter which is drying now. Maybe I can tell more by when its dry.

Andi

~andi said:

Hmm... I got some on my fingers when unspooling the film and it was kind of smeary. So why not. But how could this happen? I thought the AHL is designed to dissolve in water right? Rodinal usually takes care of that and comes out deep purple. The Neopan was outdated, but Dec 2015 isn't that long and I've developed at least 10 rolls of the same batch without black stuff.

I've run it through a coffee filter which is drying now. Maybe I can tell more by when its dry.

Andi

Click to expand...

I don't know what to tell ya Andi. It was just a guess?

Not bad one. The filter is now dry and the black stuff bonded to the paper, I can't scratch it off almost looks like black ink sprinkles now. This blasts the dissolved plastic theory and leaves the silver and AHL. The film seems fine I just sleeved it and checked under a loupe, no spots. At any rate. Not harm done. I'll keep using the acid stop next time with the same tank/cap/reels when doing neopan 400. See if it happens again...

Andi

Looks to me like bits of emulsion from fringing at the edges, due to age, damage or too-long wet time. If there's none on the film, then it shouldn't be a problem. Check your film edges/sprocket holes to see if there are tiny bits of emulsion missing.

Best,

Doremus

Way to go Doremus, that's it!

I checked the emulsion on the negs/sprocket holes which is perfectly fine. But the leader is not. I've totally forgot about it and didn't even look at it before discarding it. But that's it. Looks like a small band of emulsion was scraped off the leader.

Wet times are not excessive, in total 30min max (excluding drying time). It looks like mechanical abrasion. Maybe I wasn't careful enough when spooling the film.

Mystery solved. Thank you very much

Andi

--
PS: That's not the usual leader look, I crumpled it up before discarding.

Just a tip -- coffee filters do a poor job of removing sediment. They are designed for coffee grounds but nothing finer. Best to use lab grade rapid (coarse) filters.

~andi said:

Way to go Doremus, that's it!
I checked the emulsion on the negs/sprocket holes which is perfectly fine. But the leader is not. I've totally forgot about it and didn't even look at it before discarding it. But that's it. Looks like a small band of emulsion was scraped off the leader.
Wet times are not excessive, in total 30min max (excluding drying time). It looks like mechanical abrasion. Maybe I wasn't careful enough when spooling the film.
Mystery solved. Thank you very much
Andi
--
PS: That's not the usual leader look, I crumpled it up before discarding.

Click to expand...

~andi,

Glad you found your problem and glad to have helped,

Doremus