Black specks

mr rusty · Aug 30, 2012

Now I'm getting better at darkroom, I'm getting more particular. I sometimes (not always) get minute black specks on negs (not hairs, and am 90% certain not airborne dust). These specks are very very small and roundish - i.e. not threadlike in any way). My feeling is that it's c**p in the mains water. I have a filter I haven't fitted yet, but my question is:- is there anything else that can cause this? What have others found is the no1 cause of specks on negs apart from airborne dust?

anikin · Aug 30, 2012

You've got it right. It's c**p in the mains water. That's what I had. I once did an experiment, I let the film stay in running water wash for a very long time. The amount of c**p on that film was astounding. Ever since I've installed a 5micron filter on my photo water supply and the black spots have disappeared from the film.

degruyl · Aug 30, 2012

Also check your fixer. If there is precipitation it could deposit on your film. However, I think it is the water supply, too.

jp80874 · Aug 30, 2012

My water source is a country well. We have a water softener, but that was not enough to filter out the black specks on film.

I installed a 3 micron filter that removes specks and such from the water. It slows the flow dramatically so I only filter when I am filling the Jobo and a few gallon jugs. I got the canister type filters from a chain hardware store (Lowes) and just cut the pipes to allow it to fit. Be careful the plastic canisters are not good for very hot water. I gather the canisters melt.

No more specks on the dried film.

Good luck with the project.

John Powers

paul_c5x4 · Aug 30, 2012

degruyl said:
Also check your fixer. If there is precipitation it could deposit on your film. However, I think it is the water supply, too.

Also check the stock developer as I've had sheets ruined by precipitates in the past. I'd also be inclined to suspect the local water - You probably have cast iron pipes out in the streets unless you're on a modern estate, but even then, you would still get crud piped to your tap.

lxdude · Aug 30, 2012

mr. rusty, I suspect a clue lies in your screen name.

mr rusty · Aug 31, 2012

Thanks for the replies all. I will be fitting my filter today, so we'll see what happens.

re

mr. rusty, I suspect a clue lies in your screen name

"Mr Rusty" is the old fella in charge of the "Magic Garden", but then probably only those on this side of the pond (of a certain age!) know that!........

lxdude · Aug 31, 2012

mr rusty said:
"Mr Rusty" is the old fella in charge of the "Magic Garden", but then probably only those on this side of the pond (of a certain age!) know that!........

Well, I'm glad to hear it's not the nickname of your, uh, 'thang'.

bill@lapetelabs.com · Sep 7, 2012

Filter your water supply!

paul_c5x4 said:
Also check the stock developer as I've had sheets ruined by precipitates in the past. I'd also be inclined to suspect the local water - You probably have cast iron pipes out in the streets unless you're on a modern estate, but even then, you would still get crud piped to your tap.

Well water and city water supply's need a filter in line to remove particulate, a 5 micron filter and a y screen filter will reduce the chance of spots sticking to the emulsion and hard well water may need a water softener filter to limit the mineral content. We have a back flow preventer with a y screen filter to comply with the local water and sewer requirements and we added the particulate filter to prevent any problems such as you are experiencing!

mr rusty · Sep 18, 2012

Just an update on this. I installed a 5 micron filter (in a 10" cartridge as sold for I think fish keeping etc). The good news is the black spots have disappeared. It looks like this was definitely crud in the mains water - probably from some cast iron mains somewhere. Result!

jp80874 · Sep 18, 2012

Hooray!

John P.

Black specks

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