Soaking / washing off calcium deposits?

Tom Kershaw · Jun 30, 2018

I have two rolls of 35mm TMX film processed yesterday that seem to have missed the wetting agent stage, possibly I forgot to add it to the distilled water and I'm left with rather contaminated negatives. I've not really had this before, the only other change is I diluted the XTOL developer with tap water rather than distilled, which I ordinarily use but have successful used the tap water before.

I'm about to soak the negatives in a solution of distilled water and a small amount of wetting agent - any other ideas?

Tom Kershaw · Jun 30, 2018

Well soaking the films seem to have helped somewhat and I'll have learnt a lesson about not letting XTOL anywhere near my tap water.

Doremus Scudder · Jun 30, 2018

Tom,
If it's really calcium carbonate that's deposited on your film, a good soak in regular-strength acid stop will often dissolve the deposit. FWIW, I always soak my film for a few minutes in wetting agent/distilled water solution for the final step before hanging to dry. The harder the wash water, the longer this step has to be to get the minerals out of the emulsion. The 30 seconds recommended for the sheeting action of the wetting agent is much too short to leach out minerals in the emulsion.

Best,

Doremus

Rudeofus · Jul 2, 2018

It really doesn't matter what you mixed your XTol with, it's the final wash step with tap water which brought in the Calcium Carbonate causing these spots/stains/drying marks. You can use whatever works for getting rid of Calcium Carbonate: stop bath, Citric Acid, white vinegar, Calgon/EDTA.... Obviously you have to rewash after that and then, of course, you need the final rinse in deionized water plus wetting agent.

mshchem · Jul 2, 2018

Where I live the tap water is as hard as I've ever seen. We have a water softener which makes it usable for laundry, dishes, bathing etc. After softening the sodium carbonate content is so high, XTOL will not dissolve completely. My current house and my former place, I installed RO systems. The RO water works great.
I had a friend who wanted some fixer. We tried to mix the standard powdered F-5 Kodak Fixer, even that wouldn't dissolve in tap water.
I use RO for nearly everything.
Bedrock here is 100% Limestone, I live in Coralville Iowa. The name is derived from the bedrock
Best Regards,Mike

Rudeofus · Jul 2, 2018

@mshchem If you mix Kodak F-5 fixer with hard water, the main issue will not be Calcium Carbonate, but Calcium Borate. The same can happen with Xtol if the Calcium content overwhelms the sequestering agent. Your water seems to be a combination of hard and acidic, and Calcium Bicarbonate is quite soluble.

Sirius Glass · Jul 2, 2018

Rudeofus said:
It really doesn't matter what you mixed your XTol with, it's the final wash step with tap water which brought in the Calcium Carbonate causing these spots/stains/drying marks. You can use whatever works for getting rid of Calcium Carbonate: stop bath, Citric Acid, white vinegar, Calgon/EDTA.... Obviously you have to rewash after that and then, of course, you need the final rinse in deionized water plus wetting agent.

+1

mshchem · Jul 3, 2018

Rudeofus said:
@mshchem If you mix Kodak F-5 fixer with hard water, the main issue will not be Calcium Carbonate, but Calcium Borate. The same can happen with Xtol if the Calcium content overwhelms the sequestering agent. Your water seems to be a combination of hard and acidic, and Calcium Bicarbonate is quite soluble.

Mixed fixer with softened hard water, ion exchange resin exchanges Calcium for Sodium. So my water is loaded with Sodium Carbonate. The incoming tap water (before my water softener) pH is reported at 7.8 according to the state .There's no significant borates in Iowa water that I know of. The limestone here is so pure, Calcium Carbonate content is over 99%. Hardness is over 400 mg/L.
I think the biggest problem is my water softener, if it was straight hard water, it would not be a problem.
Without the water softener , dishwasher limes up, my wife goes crazy about scale in the bath etc. Thus my RO system.
I never had problems with unsoftened tap water for the first 25 years of processing.
You make a good point ,
Best Mike

RalphLambrecht · Jul 3, 2018

Doremus Scudder said:
Tom,
If it's really calcium carbonate that's deposited on your film, a good soak in regular-strength acid stop will often dissolve the deposit. FWIW, I always soak my film for a few minutes in wetting agent/distilled water solution for the final step before hanging to dry. The harder the wash water, the longer this step has to be to get the minerals out of the emulsion. The 30 seconds recommended for the sheeting action of the wetting agent is much too short to leach out minerals in the emulsion.

Best,

Doremus

that makes sense.You would need an acidic environment to dissolve calcium deposits; just plain water is going to do little about it.

Tom Kershaw · Jul 3, 2018

Good point. I've pretty much used a water stop for film processing without issue for a while now, will try soaking the film in stop bath. Frustrating as I've processed a fair amount of film recently with no problems, although not 35mm.

Tom

Rudeofus · Jul 3, 2018

mshchem said:
There's no significant borates in Iowa water that I know of. The limestone here is so pure, Calcium Carbonate content is over 99%.

The borate would come from Kodak F5 fixer and from XTol.

mshchem · Jul 3, 2018

Rudeofus said:
The borate would come from Kodak F5 fixer and from XTol.

Yes, of course.

Soaking / washing off calcium deposits?

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