Pyrocat-HD in Glycol: with or without bisulphite and bromide ?

[Cor]

Some time ago I posted (http://www.largeformatphotography.info/forum/showthread.php?104650-Mixing-Pyrocat-HD-white-precipitate) a thread were I mentioned that I obtained a white precipitate when mixing PyrocatHD "A" (not so in the past)

I noticed now that the mixing instructions (www.largeformatphotography.info/forum/showthread.php?104650-Mixing-Pyrocat-HD-white-precipitate) on the Pyrocat HD web site omit the metabisulphite and bromide all together and add ascorbic acid instead.

I assume that by this change to ascorbic acid the pH stays the same ?

But omitting the potassium bromide will increase B+F ?

Also: "Pyrocat-HDC gives almost identical results as Pyrocat-HD with most films and development methods."

Currently I am quite happy with Fomapan 100 in Pyrocat HD in a semi-stand regime (1 hr at 20 degC, rotate at the beginning and every 15 minutes)

Will Pyrocat HDC behave the same as Pyrocat HD in this approach?

Thanks in advance,

best,

Cor

[mgeiss]

The ingredients stay the same. I think you scrolled down too far and read the instructions for Pyrocat HDC instead of HD.

A quick copy+paste of the instructions for P. HD:

Mixing directions for one liter of Pyrocat-HD Stock A solution in propylene glycol:

Weigh out all of the chemicals for Stock A. 50.0g of pyrocatechin, 10.0g of sodium metabisulfite, 2.0g of Phenidone and 1.0g of potassium bromide.
Pre-heat 750ml of propylene glycol to about 150F in a water bath or hot plate stirrer.
Add the pyrocatechin to the warm glycol and stir until dissolved. Should take no more than about a minute.
Add the phenidone and stir. Should dissolve completely in about a minute.
Add the bromide and sodium metabisulfite to about 50-75ml of hot distilled water at about 120F. Stir until completely dissolved, and then add this solution to the propylene glycol solution.
Top off the solution with glycol to 1000ml.

Mixing Directions for Stock B:

Start with 700ml of distilled water.
Weigh out 750g of potassium carbonate and add the chemical very slowly to the water, with constant and rapid stirring. If you add the solution too fast, or don't stir enough, it will be impossible to dissolve all of it in the water. As you add the chemical an exothermic reaction takes place and the solution will warm up appreciably.
Add distilled water to 1000ml.

[Cor]

Ah you're right, I see it now, actually quite a different developer with 3 developing agents!

So my question than: how similar are Pyrocat HD and Pyrocath HDC ?

(to repeat my purpose: Fomapan 100 in Pyrocat HD in a semi-stand regime (1 hr at 20 degC, rotate at the beginning and every 15 minutes)

thanks,

Cor

[sanking]

Ah you're right, I see it now, actually quite a different developer with 3 developing agents!

So my question than: how similar are Pyrocat HD and Pyrocath HDC ?

(to repeat my purpose: Fomapan 100 in Pyrocat HD in a semi-stand regime (1 hr at 20 degC, rotate at the beginning and every 15 minutes)

thanks,

Cor

Cor,

In the Pyrocat-HDC formula ascorbic acid is used instead of metabisulfite, and bromide is omitted. General stain will be slightly less with HDC because ascorbic is slightly more efficient at keeping oxidation in check. I use -HDC for most of my regular work these days. However, results are almost identical to those with the regular HD formula, whether mixed in water or in glycol, and even with good BTZS testing you would not see much difference. Film speed is just a tad higher with -HDC because of the elimination of bromide.

Sandy

For more information see www.pyrocat-hd.com, mixing instructions, and:

B. Pyrocat-HDC (Solution A mixed in glycol)

Stock A
Propylene Glycol at 150F 750ml
Pyrocatechin 50 g
Phenidone 2.5g
Ascorbic Acid 4.0g
Propylene Glycol to 1000ml

Pyrocat-HDC gives almost identical results as Pyrocat-HD with most films and development methods.

[Cor]

Thanks for the feedback, Sandy !

Best,

Cor