TiMo
You can quite easily determine whether a fixer is suitable for film by checking the clearing time. For paper, the same test will be less reliable. I’ve read that you should hang half a strip of photographic paper in the fixer in the dark, then turn on the light, wash the strip and put it in the developer. If the half that was in the fixer remains white, the fixer and the time are fine. I tried this and also held the strip in the fixer for just 5 seconds, and it remained white after development. So the test doesn’t seem to work.
Is there another way? In my opinion, the test strips you can buy aren’t worth the expense. It’s not that I’m trying to save money on the fixer, but I want to minimise the hassle of disposal.
Ideally, of course, it would be a relatively quick test that you can carry out swiftly before starting a darkroom session.
Thanks and best regards
Tim
piu58
The simplest method:
Count it out. One litre of rapid fixer is sufficient for 20 m² or 15 m² of baryta paper. This varies slightly from product to product, but it should be stated on the bottle. You can convert this into the equivalent number of sheets of the most commonly used paper. For me, that’s 18x24. So you can process 450 sheets of PE with one litre of concentrate. If you perform dilution of 1:4, one litre of working solution is enough for a fifth of that, i.e. 90 sheets. You keep a tally of this. If a 24x30 sheet is used, that’s just 2 ticks. It doesn’t have to be accurate to the nearest percentage.
Tandemfahren
Hi Tim, Uwe,
You’re right about keeping track of the quantities, but if you want to minimise the amount of fixer you have to dispose of, you need to use a double fixer bath. In that case, the concentration is based solely on the first bath, and that can go up to 1.5–2 g/litre (!).
I use the metre rolls for this. If I weren’t too lazy, I’d keep a record of how much paper the bath can handle up to that point, and then change the bath after every so many sheets.
But then the metre rolls would just go to waste... :-)
Perhaps someone has figures on just how much less fixer needs to be disposed of (I’d guess a factor of 3).
The price of the fixer isn’t a big deal, that’s clear. My main concern is consistent fixing quality, and only double fixing delivers that. Because I’m always pulling my sheet out of a fixer that’s practically spotless and fresh.
But I think Tim’s already doing that anyway. Shall I send you a few metre-long rolls in the post to T.?
Have fun
Frank
TiMo
Haha, Uwe, the forum lifesaver. Almost always the first to reply. You should publish a book on the practical side of photography.
Keeping track is a good idea; I’d planned to do it but then forgot. Unfortunately, the description of Adofix isn’t very precise (PE or baryta) and the details all run into one another without a break. That’s why I’d like to work it out for myself.
Hi Frank,
nice to hear from you ;)
following your recommendation, I always do double fixing for film and paper. If you’d be willing to spare me a few test strips, I’d be grateful. Then I can work out the number. We’ll continue this by email.
So the method with the paper strip is unsuitable?
piu58
So the paper strip method isn’t any good?
I haven’t seen that recommendation anywhere yet.
But here’s what you can do: keep a few film snippets and measure the clearing time in the paper fixer. Of course, you must always use the same type of film – your favourite film, that is. If the time has doubled, the fixer is exhausted.
Otto
The most reliable test is the potassium iodide test:
http://www.fotografie-in-schwarz-weiss.de/sw-fotografie/tipps-tricks/29-prozesskontrolle.html#toc_1032
Best regards,
Otto!
TiMo
Thanks for the tip, Otto.
Unfortunately, chemicals are virtually impossible to get hold of locally, so I was looking for a way to carry out a test using materials I already had.
Otto
Yes, even in larger cities there isn’t a single shop left that specialises in photographic chemicals. We just have to live with that. Without mail-order services, it’s practically impossible to run a black-and-white photo lab anymore. In my opinion, the potassium iodide test is one of the most important tests in the lab. When prints start to deteriorate after about 2–3 years and you think of all the avoidable work involved in sourcing replacements, the potassium iodide test is a piece of cake.
There are two options for photographic chemicals:
- Ring round the pharmacies within a radius of about 30 km (not a big job thanks to the internet)
- Ordering from a national mail-order supplier
If you regularly process baryta paper, you should also order sodium sulphite for
the washing aid at the same time.
Best regards,
Otto!
TiMo
If I lived in Germany, it wouldn’t be a problem. But here, it’s hard to get hold of pure chemicals. I suppose they don’t trust the public to handle them properly.
I source my materials from Impex. There, you know that the money goes back into projects that support our hobby.
Best regards from Tokyo
Tim
PS: Very informative website (www.fotografie-in-schwarz-weiss.de)! Thanks for that, Otto.
Gucker
I am testing my fixer according to the instructions in the book *Larry Bartlett’s Black and White Photographic Printing Workshop*: you perform an exposure on a strip of film as normal; for this, I photographed a white surface; I then rewound the film back into the cassette and stored it in a light-tight container. You cut a small streak from the film and dip half of it into the freshly prepared fixer; you note down the time it takes for the immersed half to become completely clear (for me, usually 20–25 seconds). If you repeat the test with this fixer when it is in use, you will see that the time taken to clear becomes progressively longer; according to the book, you should discard the fixer as soon as the time taken is more than twice as long as with the freshly prepared fixer (in my case, more than 50 seconds).
michael-kielgmxnet
You don’t need to expose the test film beforehand, though. As no silver image is developed during the test anyway, it doesn’t matter whether there is a latent image or not.
Edit says: because the negative numbers have been exposed onto the film, there is already a latent image present, albeit only at the edge.
HenningH
Edit says: because the negative numbers are exposed onto the film, there’s already a latent image there, even if it’s only at the edge.
Henning asks: Do you carry out this test in the dark?
Tandemfahren
Hi,
You don’t need to do the test in the dark. The film isn’t being developed, after all. That’s why the frame numbers don’t matter either.
I still think it’s a good idea to keep the test film in a light-tight container, though, because prolonged exposure to light alters the emulsion even without development.
Personally, though, I use the metre-wide rolls and double fixing. You can’t get any safer or cleaner than that.
Best regards from Upper Bavaria
Frank
