Fixer in a pinch - Ammonium thiocyanate?

pdeeh · Sep 25, 2014

I'm away from home this week and in a home without photo-chemicals to hand (although we did find a half empty bottle of Rodinal from about 1983 that blackens film still ).

there's a small treasure-trove of vintage cameras and (very vintage) film and (extremely vintage) paper found here too, and it would have been fun to shoot a few rolls and sheets and see what it all looked like ... but of course I didn't think to bring proper fixer

So I wondered what I could do in a pinch to fix film ... if one is NOT worried about maintaining best quality or archival stability of course ... yes I know, we could always go to a pool supplier and buy hypo (except in the depths of rural Wales there are no such things as "pool suppliers", let alone anything resembling a camera shop) ...

We know that a saturated solution of table salt will fix film - sloooooooowly

I happen to have some Ammonium thiocyanate with me (for playing with fixing lumen prints), which I think is used in some colour blixes, as well as a part of the Chromoskedasic process (I'll try that too one day) and a test with a scrap of film showed a solution cleared it within a few minutes.

So I wondered what a suitable solution ratio for thiocyanate might be for fixing b&w film ... 2½% or so perhaps?

I seem to remember reading that ammonia will do something to developed film ... but I can't remember whether it fixes it or strips the emulsion off

It'll all keep 'til I get home again of course, and there are runner beans to pick and the dog to walk, so this is just me being idly curious about what one can find under the kitchen sink to fix fillum

baachitraka · Sep 25, 2014

I am using 50ml+450ml to stabilize the Lumen prints. Do not know how they work with film, since I am noticing density changes on Lumen prints(losing brilliance) etc...

jochen · Sep 25, 2014

Hello,
ammoniumthiocyanate NH4SCN forms at first unsoluble silverthiocyanate which dissolves in an excess of thiocyanate like with thiosulfate. The stability constant (pK) of the thiosulfate complex is 13.6, of the thiocyanate complex 7.9 and of the ammonia complex 7.1. The best would be cyanide with a pK of 21 but this is extremely toxic and quickly dissolves the silver too as it can be oxidized easily by the oxygen in the air because of the high stabilty of the dicyanoargentate complex. The dichloroargentate has a pK of only 5.4.
From this data I'd suggest that ammonia and thiocyanate fix much slower and need a higher concentration to shift the equilibrium to the right side, 2.5 % seem not to be sufficient.
You can try to make the clearing time test and fix 3 times of that time.
Source: Jander/Blasius; Textbook of Analytical and Preparative Inorganic Chemistry (in German).

baachitraka · Sep 25, 2014

I give like 6 mins for 8"x10" fiber paper, when no Gold toning was done before.

pdeeh · Sep 25, 2014

baachitraka, I think Wolfgang Moersch is using around 2½-5% for stabilising lumen prints, whereas yours is 10%.

jochen, if your post had been written in chinese i might have understood it only slightly less Be interesting to hear from PE or GCK or similar though.

baachitraka · Sep 25, 2014

Indeed, that may be the dilution after Gold toning.

From Facebook conversion with Wolfgang Moersch,

"Without gold toning before the stabilizer, I use two solutions of 400ml water + 50ml stabilizer.Sometimes I use a stronger 2nd stabilizer (200+50ml) depending on the paper. After gold toning a weak solution is enough, but in this case I prefer a thiosulfate fixer, because it is cheaper and it removes the untoned halides completely.If the treatment with thiocyanate is too short, there might be light sensitive halides left in the highlights."

pdeeh · Sep 25, 2014

i was going by a reply to me on his Ipernity stream.

pgomena · Sep 25, 2014

Ryuji Suzuki's fixer: (Found somewhere on the Large Format Forum)

ammonium thiosulfate 120g
(or 60% solution 200 ml)
sodium sulfite 15g
sodium metabisulfite 5g
water to make 1.0 liter
target pH 7.0 plus/minus 0.5

Paper fix time of 2 minutes, one minute each in two separate baths. Film needs 4-6 minutes in one bath.

This fixer gives rapid fixing and rapid washing, same benefit as what's claimed for alkaline fixers, but with minimum of swelling.

pdeeh · Sep 25, 2014

yes, there are many many fixer formulae available, and if I had some Ammonium thiosulfate, Sodium sulfite and metabisulfite I might make Suzuki's ... or I could make F24 if I had hypo and metabisulfite ... or any number of other fixers if I had the right ingredients

But I've only got Ammonium thiocyanate available to me this week, or table salt, or maybe some ammonia if there's some in the cupboard (as I said in my OP)

Gerald C Koch · Sep 25, 2014

Not a good idea as thiocyanates cause softening of emulsions. This would be particularly true at the concentrations needed for fixing. This was a problem with stabelization processing. The prints were very delicate until they dried.

pdeeh · Sep 25, 2014

yes, I'd seen that mentioned elsewhere by you, but as I say this is "in a pinch" processing with no regard for best practice.

It would be even worse in this case of course as the films I might want to fix are 60-70 years old anyway and won't be as hard as modern ones (if they are still recording light at all).

So ... what are the concentrations (of Amm. thiocyanate) needed for fixing?

Rudeofus · Sep 25, 2014

In the darkroom cookbook there is a fixer recipe which uses 100 g/l KSCN, so NH4SCN should work in similar concentrations. And, as suggested by Gerald and pdeeh, test carefully and make sure that your paper/film stash survives such a fixer without emulsion damage!

baachitraka · Sep 25, 2014

I have witnessed emulsion damage esp., on fiber paper when making Lumen prints. Dilution: 50ml+450ml.

Photo Engineer · Sep 25, 2014

Using about 100 g/l of Ammonium Thiocyanate will filx film, but slowly and with softening. That pretty much summarizes what was said above. That said. here are some work arounds to help!

Table salt will speed up fixing, but just by a bit and Sodium Sulfate will slow down softening (and fixing). So there are some aids that might help you out a bit.

I'll give it more thought, but if you look at the formula for my Super Fixer posted here, you will see that I used Ammonium Thiosulfate and Thiocyanate both in the same solution and that does not do anything bad.

Keep your eye out for reticulation with those old films.

PE

pdeeh · Sep 28, 2014

Thanks PE.

It suddenly occurred to me today that much of this film is so old it might even be nitrate ... I put a match to a scrap and it burned with considerable conviction and vigour :eek:

Francisbaker · Mar 6, 2021

baachitraka said:
I am using 50ml+450ml to stabilize the Lumen prints. Do not know how they work with film, since I am noticing density changes on Lumen prints(losing brilliance) etc...

I am reactivating this thread with interest in using ammonium thiocyanate to stabalize Lumens. Am I reading this correctly that one can go from a first water bath, to a gold toner using ammonium thiocyanate, then not need to go through a Hypo fixer? Thank you, Francis

NedL · Mar 6, 2021

I've used 5% sodium thiocyanate to stabilize lumen prints ( not toned in gold )... and then I left the result sitting out in light in my room for a few months to check permanence. I didn't try ammonium thiocyanate... but the sodium because of what William Jolly wrote about using it to stabilize chromoskedastic prints. It worked as a stabilizer or fixer, but I gave up on it because I was hoping to preserve the colors and it did not do that at all. Perhaps if you tone first, you will have better success ( although, honestly, I'd think you could fix in weak sodium or ammonium thiosulfate after toning )

I miss pdeeh ( who was the original poster of this thread ).

relistan · Mar 7, 2021

NedL said:
I miss pdeeh ( who was the original poster of this thread ).

Is this a case of pdeeh dropping off the forum or something we know went badly (that I missed)?

tezzasmall · Mar 7, 2021

relistan said:
Is this a case of pdeeh dropping off the forum or something we know went badly (that I missed)?

PE passed away, last year I believe. There is quite a long set of posts after his passing.

Terry S

NedL · Mar 7, 2021

I think pdeeh is doing fine, just on a break from photography.

Sorry about that, I should have been more clear. I meant that I miss pdeeh participating here at photrio.

baachitraka · Mar 8, 2021

Francisbaker said:
I am reactivating this thread with interest in using ammonium thiocyanate to stabalize Lumens. Am I reading this correctly that one can go from a first water bath, to a gold toner using ammonium thiocyanate, then not need to go through a Hypo fixer? Thank you, Francis

Yes, ammonium thiocyanate solution is kind of stabilizer for lumen prints. But that comes with two drawbacks,

1) Soften or Damage to the emulsion (noticeable at the edges)

2) Brilliance to the lumen prints are lost or not the same before the ammonium thiocyanate bath.

After the exposure it may be recommended to tone the print first and if needed then stabilize it.

Me personally don't know much about the chemistry except the recommendation by Wolfgang Moersch

tezzasmall · Mar 9, 2021

relistan said:
Is this a case of pdeeh dropping off the forum or something we know went badly (that I missed)?

tezzasmall said:
PE passed away, last year I believe. There is quite a long set of posts after his passing.

Terry S

Big ooopppss!! My bad!!

Thinking of a totally different person - hopefully pdeeh is doing fine!

Terry S

Fixer in a pinch - Ammonium thiocyanate?

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