Black Gunk/Goo

[_larky]

Hello.

I'm getting black gunk on my negs sometimes, always the roll that sits at the top of the dev tank. It looks like emulsion. It's easy to wash off, but I wonder what's causing it? Anyone had this before?

Cheers, A.

 

[Ronald M]

It is probably something that floats.

Scrub the reels and tank with a brush and wash well after each use. Store in a plastic bag between.

Water filter.

Filter all solutions including wash water. Use dedicated glass bottles for each. Do not pour anything back into a bottle.
Fix is used one time for film unless you have consecutive runs the same day. Silver precipitates from solution and sticks to next film. That is the black stuff on the bottom of used fix bottle. Use it up on test prints by syphoning off the top.



The best home filter is a filter funnel with a layer of cotton wool over the filter. It still will not capture all silver precipitate. Tiny stuff still gets thru.

 

[kbg32]

I used to filter all my reusable chemicals through coffee filters placed in a funnel when returning them to storage. Worked great and never had any problems with "stuff" sticking to my negatives.

Also make sure that your temperature is constant with your stop bath or water rinse, fixer, hypo clear, and water wash. Seems to me one of your liquids is too warm.

 

[_larky]

It seems to be something from the film itself, it peels off in perfect slices.