Stop Bath for Pyrocat?

[JBelthoff]

Hi All,

I’ve read that Sandy King uses a half strength stop bath for Pyrocat HD.

I am almost out of my ILFOSTOP which I am diluting 1:40, which I assume meets his definition of half strength, and am looking for a replacement.

I came across a recipe for Kodak SB-8 :: (15 grams of Citric acid per liter) and I have some questions which I am hoping someone can shed some light on.

• Is 15g/Liter a Stock or Working Solution?
• Assuming that it’s working, can I just mix 7.5g/Liter of Citric Acid and have "Half Strength" or is there some PH, or other, reason why this won’t work?

What I would like to do is simply toss in 7.5g of Citric Acid into a Liter of water and be on my way as a one shot solution if that is feasable...

Thanks,

[Richard Wasserman]

I use 15 grams, or 1 tablespoon, citric acid/liter as a stop bath for prints, it is the working solution. I use plain water as a stop for film with all developers including Pyrocat (which is my primary choice). I have had occasional problems with pinholes and acid stop.

[JBelthoff]

Thanks Richard. What I probably should have specified is that I am looking for an all around simple stop for film as I do not print but rather I scan my film.

So if I am using XTOL or D-23 to develop I want a full strength stop but for Pyrocat I would like a half strength as recommended. I am wondering if SB-8 would be this solution for all my needs for this?

[jp]

I just use water. two 30-second baths with agitation.

[Gem Singer]

Ilford's Ilfostop is a citric acid formulation that's readily available. Since film base does not absorb chemicals as does fiber base paper.

A rinse in plain water will remove most of the developer from the film with minimum carry over into the fixer.

The tiny bit of continued development in the water rinse is insignificant.

I've never used an acid stop bath for film developed in Pyrocat-HD. I maintain the entire film developing process neutral-alkaline with the use of an alkaline fixer.

That way, I can maintain maximum stain from the developer.

[Richard Wasserman]

John,

You can use 7.5 grams/liter of citric acid if you want an acid stop with Pyrocat. I have done that and once in a while got pinholes, which is why I now use a plain water rinse which works well. Not only do I not get pinholes, but since I use a neutral fix, the washing process is simplified. I never noticed a difference in staining between a 1/2 strength acid and water stop.

Thanks Richard. What I probably should have specified is that I am looking for an all around simple stop for film as I do not print but rather I scan my film.

So if I am using XTOL or D-23 to develop I want a full strength stop but for Pyrocat I would like a half strength as recommended. I am wondering if SB-8 would be this solution for all my needs for this?

[RichardSperry]

Doesn't acid strip some of the stain?

That's the rationale for using TF4 fix(or non acid fix), I thought.

I use water anyhow for film.

[IanG]

Doesn't acid strip some of the stain?

That's the rationale for using TF4 fix(or non acid fix), I thought.

I use water anyhow for film.

Not with Pyrocat.

I use Pyrocatechin based print developers ocassionally and tested the effects of stop baths & fixers like Hpam/Ilford Rapid Fixer (pH 5.2/5.4) and there's no differences, no loss of stain.

I use a water stop for films but stop-bath for prints.

Ian

[UlbabraB]

In the past I used both half-strenght acetic-acid based stop and plain water and didn't see any difference in the density or stain (using Pyrocat-MC in a Jobo or BTZS tubes) so I switched completely to a water stop because it fully eliminated pinholes problems on Foma and Efke emulsions.

[JBelthoff]

OK I reread the Darkroom Cookbook and found "When sodium carbonate, ..., comes into contact with acid, carbon dioxide gas is released." For now I will assume that potassium carbonate does the same.

Several solutions are offered:

• a 3% to 5% solution of sodium metabisulfite
• a 3% solution of chrome alum
• Kodak SB-1
• 10.0 grams of sodium bisufilte

Then to avoid fumes he suggest SB-8 but not for the reduction of carbon dioxide gas.

Seeing that I have the sodium metabisulfite, being an ingredient in Pyrocat HD, perhaps I will experiment with a 1% sodium metabisulfite solution and forgo the citric acid to avoid the bubbles unless someone who has tried that chimes in....

Thanks,