citric acid film hardening w/hypo-based fixer; DIY

Jan 19, 2008
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Holland, MI
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I usually look on APUG & then for technical stuff, then went to Google again today & found you folks here.

I saw new topics here, so I was inspired to sign on.

I am planning on getting back into darkroom work after 30-31 years away.

I am looking for people who have used citric acid in a fixer in place of acetic acid. Maybe it doesn't work, but I did find some discussion of it here, so I'm asking.

More info on why, and where I'm coming from and headed to...

I am going the mix-your-own route for developer based on some of the Patrick Gainer recipes.

I have bulk chemicals already. I am working on fixer questions now.

Most films, people say, don't need hardener. I have some Efke, some Foma and some x-ray films to experiment with. The first two are reportedly good candidates for hardener, and XRAY film definitely is soft, and much (but not all) of it is double-sided (emulsion on both sides).

For non-hardening fixer, I have chems for TF-2, off the top of my head, sodium thiosulfate, sodium sulfite, sodium metaborate, water.

For hardening fixer, I'm looking at Adam's F6A (on Nearly the same, with the addition of potassium alum and acetic acid.

I and my family don't want the smell of acetic acid. I am trying to use the least odorous chems possible. Easy enough with developers but takes some care with fixer. I have seen one recipe for a fixer for pyro developers that substituted citric acid but it was non-hardening.

Then I read that citric acid doesn't play well with alum, so that is probably not a viable substitute for acetic acid in an alum-containing hardening fixer.

My last resort is to use a commercial hardening fixer if hypo+capacity-odor reducer additives are not compatible...but I think I need to go custom to get absolute minimum odor.

I won't be so specific on other issues, but you can expect eccentricity from me. Make that with a capital 'E'.


zonal pro chemistry is very environmental friendly.

also sprint chemistry, vanilla and apple smells
If you are concerned about odor, just go with a commercial fix, those mentioned already, as well as Clayton or Arista products. I assume you are using sheet film? I would suggest a hardening fix for the Efke/Adox as an added precaution. The emulsion is prone to scratching if not careful during processing, but once dry it is not bad, your call here really.

The reason why the fixer formula for the pyro developer is non-hardening is that most pyro based developers act as a hardener already.

Overall you should be fine with a commercial fixer, fine tuning your developer is where you should concentrate your efforts.

Unless you have specific goals by mixing your own fix?

Here is the formula for OF-1, style of rapid-fix, fairly odorless which can be fine tuned by adjusting the alkali:

600 ml water
220g Sodium thiosulfate pentahydrate
30 g Sodium sulfite anhydrous
40 g ammonium chloride
20 cl Sodium metaborate 10% solution OR 5 g Sodium bicarbonate

Water to make 1 liter.
OF-1; is that Ole's from Norway?

Great, thanks! I have all the stuff except the NH4Cl(x).

My goal is to use all the bulk stuff I already have :O) One more chem is OK; I won't feel as stupid as having wrong stuff with no use.

Thank you.

I will check out the scented ones too however.

Actually, I've been convinced to not bother with hardener... on the principle it only works during wet handling; once dry, hardened film is no harder than unhardened fim, but is harder to tone, etc.

So I can just simplify things.

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