I'm using PMK pyro and to minimize stain loss during processing I'm using plain water stop and a non-hardening fixer (Kodak F-24 formula). Is there a formula available for mixing a fixer which is less acidic or even alkaline? I assume that this would maximize stain. (I'm in Australia and would prefer to mix myself rather than import small quantities of pre-mixed fixer from the USA)

-- John Stockdale (jjss@bigpond.net.au), May 27, 2001

Answers

Here is a formula for TF3 alkaline film fixer. 800ml of Ammonium thiosulphate (57-60%), 60gms of sodium sulfite and 5gms of sodium metaborate. Add water to bring the volumee up to a litre. Dilute 1:4 for a working solution. Cheers, DJ.

-- N Dhananjay (ndhanu@umich.edu), May 27, 2001.

Thank you very much for the above suggestion. I'm having difficulties locating Ammonium Thiosulphite here, but with luck I'll fond some.

-- John Stockdale (jjss@bigpond.net.au), May 28, 2001.

Ammonium Thiosulphate can be created in solution by mixing Sodium Thiosulphate (plain Hypo) with Ammonium Chloride. Ammonium Chloride is commonly used as a fire retardent treatment.
The ratio is 40 parts by weight Ammonium Chloride to 60 parts Hypo, if my memory is correct. This reacts to form Ammonium Thiosulphate and common salt. The Sodium Chloride takes no part in the fixing action.

-- Pete Andrews (p.l.andrews@bham.ac.uk), May 29, 2001.

Thank you Pete. I used my schoolboy chemistry to check this. I hadn't thought of doing it this way, but it makes sense. Your calculation is correct (the sod. thiosulphate quantity refers to the anyhdrous form), and for 1000g of ammonuim thiosulphate, you need 1080g sod thiosulphate. This also produces 800g of sodium chloride, which one would guess is probably benign. However, on Jack's Photographic and Chemical Site (www.jackspcs.com) he states for sodium chloride:

Uses: As an ingredient in the precipitation of photographic emulsions; as a silver halide solvent in fine grain developers; as an ingredient in reducing and toning solutions; as a washing aid to eliminate residual thiosulfate from silver images.

A silver halide solvent is not exactly what I'm looking for in maximizing the effects of PMK. In a rapid fixer, would it have any discernible effect?

Thanks to all for their interest in responding

-- john stockdale (jjss@bigpond.net.au), May 29, 2001.

John, an excellent place to look for chemicals is swimming pool supply companies. I dont know if they would have ammonium thiosulfate, but they do have sodium thiosulfate and a large variety of other bulk chemicals that can be used for photography. And cheap, too! They have almost everything except reducing agents.

-- Wayne (wsteffen@skypoint.com), May 29, 2001.

With regard to John's question about solvency effects of sodium chloride. Yes, sodium chloride is a silver solvent and is used in a few developers for this purpose. However, I don't believe its going to affect anything when preseent in the fixer. That's because by the time film has reached the fixer, image bearing silver halide has been converted to silver. The remaining unexposed silver halides are to be removed i.e., fixed. I'm pretty sure sodium chloride does not influence the silver image. Now, of course, the use in a developer is a differeent ballgame altogether since the sodium chloride can dissolve image beearing silver halide beforee they can be acted on and reduced to silver. Good luck. Cheers, DJ.

-- N Dhananjay (ndhanu@umich.edu), May 30, 2001.

You can buy alkaline fixer readymixed: Agfa Universal Fix (for Color C-41, but it works well).

-- Anders Ocklind (miramax@algonet.se), May 31, 2001.

Thanks Anders, Have you used it for B+W negs? According to Agfa's instructions for C- 41 colour neg processing, it's diluted 1+5 for use, making it cheap enough for one-shot processing, which appeals to me. Are there any ingredients in it that might cause unforseen consequences? Its density after dilution is supposed to be 1.069 making its density before dilution about 1.41 if my arithmetic is correct. This would make it somewhat less concentrated than TF-3 stock.

-- john stockdale (jjss@bigpond.net.au), May 31, 2001.

I use Agfa Universal Fix (C-41) 1+4 for B&W films and the same for B&W paper. Substitute 20% of the volume with fresh fixer after each filmdeveloping. Paper:I use 2 bath method and measure the silvercontent with Kodak silverteststripes. Anders O

-- Anders Ocklind (miramax@algonet.se), June 01, 2001.