Fixer - silver content test strips

Hallo,

As part of my somewhat random and on-going thinking about the fundamentals of b/w printing (sounds rather grand that! - more like questioning what I think I know) I got a pack of Ag-Fix strips from Silverprint:
http://www.silverprint.co.uk/ProductByGroup.asp?PrGrp=523 (top item)

The instructions are clear but analyzing the results are less clear. There are 7 colour patches for Ag content from 0.5 g/l Ag to 10 g/l Ag. The test strip changes colour depending on the level of silver in the fixer. But what is the "unsafe" level? The instructions do not state at what level of silver grams per litre makes the fixer unsafe to use/past its viable life/need replacing etc.

Can any one assist with specifying what level of silver grams per liter is "unsafe"?

It also has indicators for pH levels between 4-8, if that is of any help.

Just trying to move away from trying to remember how many 10x8 prints have gone throught the fixer before replacing!

Sim2.

The safe silver level depends on your standards. If you have a look at Ilford's Rapid Fixer datasheet (page 4 of 5), you'll see some silver concentration levels for various applications.

To be honest though, I'd rather buy the HT2 test solution. IMHO, it's far more important to know if your FB print is properly washed, than knowing the silver level in your fixer solution.

Yes, HT2 is more reliable, as the fixer test strips can vary in result depending on fixer ingredients. Also, the wash water affects the final result which HT2 picks up!

PE

Anon Ymous said:

To be honest though, I'd rather buy the HT2 test solution.

Click to expand...

Lol! I got that as well!

My thoughts were to try to keep track of the "deteriation" of fixer as I use it for prints to see if this matches or is close to my non-scientific method of keeping track of the number of prints that have been through the fixer, and dumping when a certain volume has been reached.

The HT2 test is part of my overall questioning but maybe more to do with the effieciency of the wash than the "potentcy" of the fixer - a print may be washed
to "archive" standards ok, but if the fix was knackered the HT2 will not pick thi up, correct or a wrong assumption. Sort of trying to get the benchmark for properly fixed prints (i.e. not underfixed in exhausted fixer) before the wash process.

Cheers for the replies and thanks for any more inputs.

Sim2.

I use the Ag test strips as one of two checks on my fixer (the other is a simple film clearing-time test) and dump the fixer if the silver content reaches 1g/l (Ilford recommend 0.5g/l IIRC for "archival" fibre paper). In practice, I dump the fixer before then as my self-imposed clearing-time rule dictates that I dump it when the clearing time becomes 50% longer than with fresh fixer - this always seems to happen somewhere between 0.5 and 1g/l according to the test strips.

I also use the HT2 test which is fine for testing washing, but it's no use having a well-washed print that is not sufficiently fixed. Once I have done the HT2 test for one particular paper I know my normal wash method is working OK for that paper and do not bother to do it again unless I have an "issue" when toning for example (which has never happened, but then I'm not the most prolific printer!).

The retained silver test should be used to check the condition of fixation of the film or paper.

PE

Bob F. said:

I use the Ag test strips as one of two checks on my fixer (the other is a simple film clearing-time test) and dump the fixer if the silver content reaches 1g/l (Ilford recommend 0.5g/l IIRC for "archival" fibre paper). In practice, I dump the fixer before then as my self-imposed clearing-time rule dictates that I dump it when the clearing time becomes 50% longer than with fresh fixer - this always seems to happen somewhere between 0.5 and 1g/l according to the test strips.

I also use the HT2 test which is fine for testing washing, but it's no use having a well-washed print that is not sufficiently fixed. Once I have done the HT2 test for one particular paper I know my normal wash method is working OK for that paper and do not bother to do it again unless I have an "issue" when toning for example (which has never happened, but then I'm not the most prolific printer!).

Click to expand...

Thanks for this - very clear explanation.
Perhaps I should have checked the Ilford site! :rolleyes: but good to hear "real" usage info. Having done my rough counting procedure on the last lot of fix and run a test strip it looks a bit like I will have to dump the fixer sooner.

I agree with your description of the HT2 test, perhaps better written than my waffling.

Cheers, Sim2.

Anon Ymous said:

To be honest though, I'd rather buy the HT2 test solution. IMHO, it's far more important to know if your FB print is properly washed, than knowing the silver level in your fixer solution.

Click to expand...

I'd rather know both. The different tests give you different data about your process, and thus are not an "either-or" choice but might better be seen as complementary. I want to know my fix is in good shape, and I want to know my prints are well washed.

CBG said:

I'd rather know both. The different tests give you different data about your process, and thus are not an "either-or" choice but might better be seen as complementary. I want to know my fix is in good shape, and I want to know my prints are well washed.

Click to expand...

BTW: I seriously hope you're using a second bath.

- Situation : Two bath fixing method and FB paper. When in the first bath the Ag level to high, it is discarded and replaced by the second one, the second will then be a fresh one.
- Supposition : In the first fixing bath the Ag level is about to be to high and in the second fixing bath the level is 0 g/L.
Because, in this case the first bath, for an unknown and hopefully short time, has a rather to high Ag and “other compound" contend just before it is discarded.
With a to high level “…compounds may remain in the paper base after washing and over time possibly contribute to print staining…” (dixid Ilford’s Rapid Fixer data-sheet).
- Question : Does the second bath corrects the eventual possibility of an issue due of the higher Ag contend, and other compounds, of the first bath?
Does this concerns neutral to alkalic fixer too, particularly the issue of the “other compounds”?

I hope you understand what I am trying to say…

Philippe

P.S. Is there a formula to brew your own HT2 test solution?

CBG said:

I'd rather know both. The different tests give you different data about your process, and thus are not an "either-or" choice but might better be seen as complementary. I want to know my fix is in good shape, and I want to know my prints are well washed.

Click to expand...

It's true that a print is well processed as long as it's both well fixed and washed. The HT2 test takes care of the later, retained silver test can easily be done with selenium toner, which every serious printer should have. However, I think that the hypo test (5% potassium iodide solution) can replace the silver estimator papers when using two bath fixing. IME, it doesn't take long to get precipitate when using this test. I don't know the exact silver level when precipitate starts to form, but keep in mind that the second bath will have far lower silver level. Thus, the combined effect is that the print doesn't spend a lot of time in a silver laden solution. So, these papers are ok, but IMHO rather unnecessary if you do the other tests and use the two bath method.

@leicam5

HT2 test formula:

150ml water
25ml acetic acid 28%
1,5g silver nitrate
water to make... 200ml

Store in a brown glass bottle, away from light.

While I use HT-2 for testing washing and also occasionally use the sodium sulfide test for retained silver, I usually rely on two-bath fixing to take care of ensuring that the prints/films are adequately fixed. For small batches of film, however, I still use one-bath fixing. I've been using the following methods for quite some time now, and submit it to the experts here for feedback (PE in particular, if he would be so kind as to comment). My techniques follow:


One-Bath Method for Film:

I use this for small batches (6-12 sheets at a time). First, I do a clip test with the film I am working with to determine clearing time. My technique for this is to put a small drop of fresh fixer on a strip of film, wait 30 seconds and then immerse the entire strip in the fixer with agitation. I observe this under good illumination until there is no discernible difference between the clear spot started by the drop of fixer and the surrounding film, i.e., till both dot and surrounding area are equally clear. This time is then the clearing time.

I fix for minimum three times the clearing time to ensure adequate fixing (not twice the clearing time as many recommend). This is based on information from Bill Troop/Steve Anchel in The Film Developing Cookbook or The Darkroom Cookbook (can't remember which one now...). Often I use the manufacturer's minimum time if it is greater than 3x the clearing time. I repeat the clip test before each batch/roll to determine the new time, using 3x the clearing time as a minimum. I discard the fix when the clearing time reaches twice that in fresh fixer.

The two-bath method for film is the same as for prints below; I just make sure to use the same film as I'm developing.

Two-Bath Method for Films and Prints

I first mix two fresh fixing baths. I then do a clip test using film to determine clearing time. For film, I determine minimum fixing time as above: three times the clearing time in fresh fix, but now divided between the two baths. For prints, the clip test is just a measure of how the first bath is doing. I determine my fixing time by using the maximum manufacturer's recommended fixing time for a given dilution and dividing it between the two baths.

For both films and prints I now use normal rapid fixers, usually Ilford's Rapid Fix. I use the stronger dilution for film, but find it easier to use the "print dilution," i.e., 1+9 with Rapid Fix, when processing fiber-based prints. This gives me 1.5 minutes per bath plus drip time for prints.

I then keep track of the clearing time in the first bath by doing occasional clip tests (with the same film, of course). When the clearing time of the first fixing bath reaches twice that of fresh fixer, I discard it and replace it with the second bath (which then becomes bath one). I mix a fresh bath two.

I proceed as above for up to three changes, then discard both baths and start again. I know Kodak states that the procedure can be done up to seven cycles, but I rarely have a throughput that justifies that.

That's it. Comments from the expert's please?

TIA

Doremus Scudder
www.DoremusScudder.com