Agfa FX-Universal Fixer

[Mark Layne]

Hi
Having read that FX-Universal is an alkaline fixer I decided to try some.
When I test it with a pH test strip it reads 'weakly acidic'
Any thoughts on this

Mark Layne
Nova Scotia

 

[Bruce Osgood]

These are recommendations of working strength solutions provided by Ryuji Suzukia, a highly regarded chemist of B/W photography.

developer (bw): pH ~9
stop: pH 3-5.5
fix: ~pH 5

 

[Robert]

http://www.agfa.com/photo/products/pdf/C-7094-E3.pdf

Claims pH 7.3. What kind of water did you mix it with?

 

[Mark Layne]

It was mixed with tap water

Mark

 

[Robert]

Depending on what your water is like that could explain the difference in pH.

 

[john_s]

I am not a chemist, but I would expect that a liquid fixer would be fairly well buffered against pH changes due to normal water variations. According to Ryuji Suzuki the measurement of pH of photographic solutions is difficult with pH meter unless you have a special probe. He does actually recommend indicator papers. I wonder if your indicator papers are good for such a strong mixture of chemicals. See

http://silvergrain.org/Photo-Tech/experimental.html

FX-Universal is supposed to be slightly alkaline, no more so than much tap water. It is not supposed to be conspicuously alkaline. It is sufficiently not acidic to give the obvious benefits of alkaline fixers (especially no SO2 odour) but not so alkaline that emulsion softens noticeably.

As far as your indicator papers are concerned, I don't know why you got the reading that you did. What make/type are they?

 

[Mark Layne]

On taking another look at this I checked the tap water and it does read acidic.
Testing the undiluted fixer does give a weakly alkaline reading-just barely.

The tap water does seem to give other problems. Arm and Hammer sodium carbonate dissolved in it gives copious precipitated sludge and does not develop Jand C 200 in the times recently posted by Sandy

Mark

 

[glbeas]

Have you had the water tested to find out whats really in it? Sounds like you need to mix all your chemicals in distilled water.

 

[Robert]

The carbonate is dropping out of suspension. That stuff likes to drop out.

Just use distilled water to mix with.

 

[glbeas]

Actually seems to me theres a lot of metals in the water and the sludge wouuld be metal carbonates. The sodium carbonate dissolves very readily. If distilled is not available maybe a bit of water softener to remove the metal sludging. Anybody know how that is handled if your system doesn't have a water softener?

 

[Aggie]

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