Sulfite-free fixer

eclarke · Feb 22, 2007

My friend and neighbor seems to have a sulfite allergy and may be forced out of his darkroom. Does anyone have a sulfite-free fixer formula???..Evan Clarke

Photo Engineer · Feb 22, 2007

Any fixer can be mixed without sulfite, they just have poor keeping.

The lower the pH, the worse the keeping.

Mix in small quantities and use immediately. My favorite would be about 200 ml / liter 60 % ammonium hypo and adjust to pH 6.5 with 28% acetic acid. Use within a week of mixing.

PE

jim appleyard · Feb 22, 2007

Check the chemstry section here. You'll find some fixers with low amounts of sulfite.

I must ask, how is your friend coming in contact with the fix? Gloves would prevent skin contact. Besides, developers contain sulfite as well, so I think you'll need to look beyond the fixer.

Photo Engineer · Feb 22, 2007

Developers can be made without sulfite as well, with the same caveat. They will not keep well.

PE

gainer · Feb 22, 2007

Photo Engineer said:
Developers can be made without sulfite as well, with the same caveat. They will not keep well.

PE

Unless you make stock solutions in organic solvents like propylene glycol or triethanolamine.

Photo Engineer · Feb 22, 2007

Two part sulfite free developers, no matter what the solvent, once mixed for use will only last for an hour or so. So, your statement only applies to two part developers or single part concentrates with no water present.

That should be made clear.

PE

john_s · Feb 22, 2007

If the problem is sulphur dioxide that emanates from fixer into the air, this can be minimised by having the pH around neutral. It is acidic fixers that give off lots of SO2. The old Agfa FX-Universal with pH=7.5 was probably ideal. Kodak Flexicolor has pH=6.5 and is not bad at all. Don't worry, your darkroom will still smell like a darkroom, but not nearly as strongly.

eclarke · Feb 22, 2007

jim appleyard said:
Check the chemstry section here. You'll find some fixers with low amounts of sulfite.

I must ask, how is your friend coming in contact with the fix? Gloves would prevent skin contact. Besides, developers contain sulfite as well, so I think you'll need to look beyond the fixer.

My friend has problems with fruits like grapes, cherries etc and it has been getting worse in recent years. He was thinking metol but the symptoms are hives and irritation of the throat, he has had no contact dermatitis. We now think just the exposure to whatever fumes are being released may be the cause. We have developer formulas which are sulphite free and just want to eliminate it completely from the scenario and see the result. He is running a 2000 sq. ft. capacity activated charcoal air cleaner but when over a tray of Dektol the symptoms start.

PE, thanks that makes good sense, nice and simple and easy to do. What kind of fixing time do you think is appropriate for FB paper?..Evan Clarke

Photo Engineer · Feb 22, 2007

I would use about 30% longer than used with TF-4 fixer with the one above.

Use about 30% longer wash also compared to TF-4.

PE

Photo Engineer · Feb 22, 2007

As for the hives and things, I would suggest that he keep a bottle of liquid benadryl in his home, and take a small dose every time the problem appears. This is often recommended for allergies to prevent the throat from swelling shut. It is also useful in the case of bee stings.

A benadryl lotion is also useful to apply to the hives.

PE

jim appleyard · Feb 22, 2007

I am out of suggestions, but I do hope your friend finds a quick and easy solution to his problem. It would be a shame if he could no longer enjoy the darkroom.

gainer · Feb 22, 2007

I have had sulfite free paper developers last for several hours. Be that as it may, the possibility of using a developing tube should be explored. The developer used is only enough for the one print. same with the fix. It does not need to be part of an expensive developing machine. When I want to make a print that will not fit in my trays, I use a tube. It takes only a few ounces that can be mixed as needed. I roll the tube on a table, pour out the developer and pour in the fix. Both developer and fix can be sulfite free.

Of course, it eliminates development by inspection. I don't see much difficulty there, as I have never had a successful print that I jerked before completion.

dancqu · Feb 23, 2007

gainer said:
...pour out the developer and pour in the fix.
Both developer and fix can be sulfite free.

Develop fix. No stop. Rotary processing one-shot.
I process the same way but with a tray and minimal
solution volumes of more than the usual dilution. I
thought 1:7 was very dilute but a thread a while
back mentioned using it at 1:9; rotary.

At those dilutions, 1:7 or 1:9, even a very sulfited
developer should be safe. Sulfur dioxide is very
soluble in water. Of course developers are
alkaline and not given to out gas SO2.

My fixers are fresh each print and need no
sulfite. Also they are a little alkaline. All
chemistry one shot. Not so given to
mass production but if a few prints
per session will do ... . Dan

Sulfite-free fixer

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