plain hypo fixer questions

I'm tired of mail-ordering rapid fixer. It's the last remaining chemical that I can't mix up myself and that I risk running out of.

I bought 5lb of sodium thiosulfate pentahydrate. Following some instructions online, I mixed up 240g of hypo and 30g of sodium sulfite in 1 liter of water. It fixed film quite fast and I shall try to keep it and reuse it.

Questions:

What is the risk to my film? If I follow the common advice to fix twice as long as it takes the film to clear, is there really any danger to my film from the fixer going off or being over-used? Wouldn't it just fail to clear the film in a reasonable time, prompting me to mix up more?

See above, but for RC paper. Since I can't see easily how the paper is clearing, maybe I could mix up fresh fixer every printing session. Does anyone else do this?

Fixer becomes unusable in two different ways:

1) it loses chemical activity; and
2) it becomes saturated with fixed out silver.

It is possible that you could have used fixer that still is capable of the necessary chemical activity (short clearing time) but the concentration of fixed out silver is too high.

There are chemical tests for both problems. If you are making up your own fixer, I would suggest you do those tests - at least until you arrive at your own capacity guidelines.

With respect to RC paper, I would mix it fresh each time.

Why not just keep a package or two of the Kodak powder fixer on hand. Then if you exhaust your supply of liquid fixer, you could easily mix up a package of powder fixer and continue working. The packages should keep for years.

Sodium thiosulfate (hypo) fixers are slower in their action than ammonium thiosulfate based ones. Their capacity is also lower. However one must always weigh the pros and cons of any choice. Certainly cost is one of them.

There are a couple of recipes on APUG which use hypo but also add ammonium chloride to the formula. The resulting fixer is slower than a rapid fixer but faster than a plain hypo one.

Gerald C Koch said:

.....Certainly cost is one of them.

.....

Click to expand...

I have used C-41 fixer for years for black and white films and papers because it was cheaper and not as smelly as acidic fixers. Now the cheapness is no longer, at least here in Australia, so I will soon be using the simple fixer referred to above, perhaps with a bit of ammonium chloride. Cheap fixer has the advantage that one is less tempted to stretch its use with its serious downside: contaminated prints.

I omit the sodium sulphite and use a bath A bath B.

When the time to clear milky gets longer I discard bath A when it is longer than 5 mins at 20C with non tabular.

I open the tank after 3 mins and inspect

The Kodak F24 formula may be better forgotten exact number but it has meta to make it more acid.

If it is older than a few weeks I start again cause I use multi tanks and large batches this is not wasteful.

Xmas said:

The Kodak F24 formula may be better forgotten exact number but it has meta to make it more acid.

If it is older than a few weeks I start again cause I use multi tanks and large batches this is not wasteful.

Click to expand...

In the older Eastman Kodak Reference Manuals F24 was the only non hardening fixer listed, and described as "for special purposes". Kodak Ltd (UK) published F25 instead which uses Potassium Metabisuphite, again it was described as "for when hardening is not desired, or must be avoided , e .g., with 'Transferotype ' and Bromoil papers.


Kodak F52 Non Haqrdening Fixer*

Sodium thiosulphate (hypo) 250.0 g
Potassium metabisulphite 25.0 g
Water to make 1 litre


*As an alternative to preparing your own fixing bath , 'Kodak' Rapid Acid Fixer is available in powder form.


On one of my trips back from Turkey about 4 years ago I ran out of Hyopam and having no Ammonium Thiosuphate in stock made up a Rapid fixer like Gerald mentions using Sodium Thiosulphate and Ammonium Chloride, I was quite surprised how fast it worked, not much slower than Hypam or Ilford Rapid fixer. This was the formula I used:


Agfa/Orwo 304 Rapid Fixer

Sodium thiosulphate (hypo) 200 g
Ammonium Chloride 50 g
Potassium metabisulphite 25 .0 g
Water to make 1 litre

Ian

That's interesting Ian.

When I ran out of rapid fixer a few months ago, but had some hypo to hand, I made up a batch from the F-24 formula in Kodak publication J-1 , which is given as

Sodium thiosulfite penta 240g
Sodium sulfite anh 10g
Sodium bisulfite anh 25g

(Although I used metabisulfite)

J-1 says it is "suitable for films, plates, or papers where no hardening is desired"

Thanks guys

and I keep meaning to get the ammonium salt but always put it off.

Plain hypo fixers don't keep long. Don't keep it overnight. With sulfite added, it will last longer, but test often. You can use a film clip-test as a general test for fixer exhaustion; twice the clearing time in fresh fixer = exhausted fix. Discard the fixer.

When fixing film, use a clip test as an indicator of exhaustion as above. Use an acid stop to avoid stains. Clip-test before each batch. Fix films for at least three times the clearing time or at least three minutes. Longer won't hurt. No risk to your film if you stick to the clearing-time guidelines.

When fixing prints, you need to establish a capacity. In lieu of manufacturer's recommendations or your own testing, 20 8x10s per liter is a safe limit for RC prints using a one-bath method. Use an acid stop or prints may stain.

If you have access to residual silver tests, then fix away, testing as you go until you find a print that shows residual silver. Use that number of prints plus a generous safety margin as your maximum capacity and refix the last few prints you made in fresh fixer. Then, test the last print through your fixer on a regular basis to check your workflow. Some advocate using a film clip test for determining exhaustion of print fixer. I imagine this would work but I'm not sure, since film can tolerate much more residual silver in the bath than prints. It would likely be okay for RC paper, since it is basically film with an opaque base... Maybe one of the chemists would like to confirm or deny this? Gerald?

Plain hypo fixers make good fixers as a second bath just before toning. You can transfer the prints directly to the toning bath.

If you are just tired of mail-ordering and want to mix your own fixer, there are lots of recipes, including the ones that Gerald mentions above, that you can mix yourself and that will last longer. Here's and easy one.

TF-2 Alkaline Fixer
Water at ca. 50°C: 750ml
Sodium thiosulfate: 250g
Sodium sulfite: 15g
Sodium metaborate: 10g
Water to make: 1 liter

Capacity: 20 8x10 films or prints (or equivalent) per liter.

If you work with fiber-base prints, use two-bath fixation and establish a testing regime. It's the only reliable way.

Best,

Doremus