A simple fixer formula. Any opinions?

kodachrome64 said:

I'm very interested in doing this. I have a couple of questions:

1. If I make a one-shot fixer, would it be better to use sodium thiosulfate or ammonium thiosulfate? The latter would be a rapid fixer and much faster, correct? Is there any reason to use one over the other? Both are available from Photo Formulary and are very close in price for 1lb containers.

2. I wouldn't want to bother with using a scale before every session, so would it be possible to use a volume measurement, taking a bit from a jar of powder and mixing it with 500mL of water? I'm sure accuracy is not that vital here.

This is really appealing to me to be able to fix my negatives to the highest archival standards and to not have to mess with reusing fixer. Also the cost savings should be significant since fixer is my highest expense with developing film.

Thanks,
Nick

Click to expand...

Nick, as I've suggested twice, a lot of your questions are answered, directly or indirectly in the pdf that I linked to above.

Dry ammonium thiosulfate is a lot more expensive than the liquid, per pound and including shipping. This is in my paper.

Re-use fixer w/o concern. In fact, I would say that you have a far greater chance of insufficient fixing - especially with T grain films - with a dilute throw away fixer than re-using undiluted fixer. All you need to do is test it with a strip of film when new, then periodically during its life. When you get a signicant increase in clearing time, ditch it.

Sodium Thiosulfate Penta, 1 pound per gallon of distilled water. Paper is one minute for fiber with constant agitation. Film is 5 minutes. Pat

Very informative paper Paul. So the fastest fixer was a 25% solution of the 60% ammonium thiosulfate. I don't really care how I mix it; in fact, liquid will probably be easier since I'm not going to buy a scale just to mix up some fixer. I am going to try all of the different ways to see which I like best.

Why would you say that reusing fixer would be more archival than using a one-shot dilute fixer? If anything I would think they would at least be the same, but IDK. I can't imagine it would be harmful to use fixer this way. Currently I do reuse Hypam fixer (and Kodafix, with older emulsions) and I know when to throw it out. I also use hypo check occasionally but it's not really necessary.

I have not used it but this formula is in one of my books:

Gevaert G-301 Acid Fixing Bath

Sodium Thiosulfate Na2S2O3 250.0 grams
Potassium Metabisulfite K2S2O5 or Sodium Metabisulfite Na2S2O5 25.0 grams

Water 1.0 liter

My Source: Darkroom Handbook and Formulary by Morris Germain, ARPS, page 39, Published and copyrighted 1940 by Ziff-Davis Publishing Company.

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Well my hope is to be able to do a one-ingredient fixer...if I can't do that then I'll just buy Hypam by the 5 liter jug.

kodachrome64 said:

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Well my hope is to be able to do a one-ingredient fixer...if I can't do that then I'll just buy Hypam by the 5 liter jug.

Click to expand...

The simple one ingredient fixer i use is ammonium thiosulfate. I use 10% times three minutes for film, and 5% times two minutes for paper.

lensmagic said:

The simple one ingredient fixer I use is ammonium thiosulfate.
I use 10% times three minutes for film, and 5% times two
minutes for paper.

Click to expand...

Ammonium thiosulfate alone is rapid fixer. It is rapid because
the ammonium ion will complex with some of the halides of silver
found in film and paper emulsions; silver chloride, silver bromide,
and silver iodide. The degree with which it will complex decreases
in the order listed. The ammonium ion has very nearly zero affect
upon silver iodide. As is well known rapid fixers are no longer
rapid when they encounter emulsions containing silver iodide.

For darkroom work we are dependent upon the thiosulfate ion.
The ammonium ion is by itself a poor fixer; at best good only
for the chloride of silver. The cyanide ion is the ONE other
ion which shares the thiosulfate's affinity for silver.

Any fixer ingredients other than sodium or ammonium
thiosulfate serve as ph modifiers, preservatives, or
ph buffers. Any one ingredient will, for some
purposes, serve in all three capacities, ie
sodium sulfite.

Contrary to some thinking the ammonium ion contributes
little additional capacity. Due to it's great affinity for silver
it is the thiosulfate ion which loads up. That is more the
case where bromide is present, and as mentioned, very
nearly the entire case where iodide is present. Dan

Dan;

Thiocyanate is an excellent fixer, quite on a par with thiosulfate ion. Non-ionic fixing agents abound as well! This includes Thiourea and others as well. A number of these appear in patents.

Ammonium Silver Iodide complexes do form and are claimed in our blix patent for films. Iodide can even speed up the complexation of Silver Halides in the presence of Hypo and Thiocyanate. Ammonium Thiosulfate Silver halide complex salts do form and the Ammonium ion assists in silver ion removal.

Ammonium Bromide in Bleach baths shift the equillibrium to the right (more solubility) and accelerate bleaching of color films.

Ammonium ion increases rate dramatically, and increases capacity by a small but real and measurable amount. Iodide can speed or retard fixing depending on the amount present in the fixer and emulsion. Below a given value it speeds the rate, at another value the rate is not affected, and above a given value it slows fixation.

PE

FWIW, Anchell's Darkroom Cookbook, 2nd Edition has a formula (#126, Defender 9-R Rapid Thiocyanate Fixer) for a fixer based on potassium thiocyanate:

Water: 600ml
potassium thiocyanate: 100g
potassium alum: 50g
add water to make: 1l
once above is dissolved, add:
acetic acid, glacial: 25-35ml (see below)

The instructions say that the fixer works in just 20 seconds at room temperature (defined as 65F/18C or above), and it also works at much lower temperatures (as low as -23F/-7C, with a 4-minute fixing time). The instructions don't specify different fixing times for film vs. paper. The 25ml figure for acetic acid is for room-temperature fixing, 35ml for low-temperature fixing.

The instructions say that potassium thiocyanate is a skin irritant, so gloves should be worn when using this fixer.

Personally, thiosulfate (particularly ammonium thiosulfate) works fast enough for me, so I don't plan on messing with potassium thiocyanate fixers.

What is the advantage of buying the raw materials, measuring the raw materials, and and mixing them for fixer that is readily available and inexpensive to buy?