At what level of Ag g/L should I replace fix?

[angusparker]

I ordered Ted's suggestion. http://www.ctlscientific.com/cgi/dis...item_num=90741

I use and reuse TF-5 for film only and have not found it's exhaustion. It always clears quickly, I go by time. I store it in 5-gallon tanks pouring the used back in. I guess I better find out where it fails the Kodak parameter.

Testing with Edwal Hypo Check reveals nothing, no exhaustion...

Got a nasty shock when I tested mine - 5g/l which is 3 times the limited according to what is written above. Nothing really critical I've been doing lately on the film side which is good. Just playing around with my new old 11x14 so if the negatives fade etc I'm not too bothered.


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[Tin Can]

Got a nasty shock when I tested mine - 5g/l which is 3 times the limited according to what is written above. Nothing really critical I've been doing lately on the film side which is good. Just playing around with my new old 11x14 so if the negatives fade etc I'm not too bothered.


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I do a lot of X-Ray which is quickly given away to another person who wants negatives for other uses.

I keep a loose track of total sq ft and replace when suggested.

Everything I do will never be saved for eternity.

I'm trying to find the min/max with X-Ray.

[Tin Can]

Got a nasty shock when I tested mine - 5g/l which is 3 times the limited according to what is written above. Nothing really critical I've been doing lately on the film side which is good. Just playing around with my new old 11x14 so if the negatives fade etc I'm not too bothered.


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I tested 2 well used TF-5 batches with the strips.

Both TF-5 and never mixed together. Both 0.5 AG and PH 7.

[Doremus Scudder]

Keep in mind that there are different standards of acceptable dissolved silver in fixers for film and for paper. Film fixer can have a lot more silver in it and still do the job just fine. However, you don't need fancy test strips for film fixer; just do a clip test and keep track of clearing times. Toss the film fix when clearing time for a particular film is 2x that in fresh fix.

For fiber-base prints, the whole situation is more complicated. If you want archival permanence, use two-bath fixing and toss the first fix before its throughput capacity has been reached. This keeps the second bath fresh. You can also use a single-bath regime, just remember that the fixer capacity is kind of low (10 8x10s per liter or fewer). Test for residual silver/hypo too to check your process. Even these tests won't tell the whole story. It's best to "underuse" the fix and be sure.

Angus, I imagine that using the first print fix to 1.5g dissolved silver and then changing out would be a good starting point. You might be able to go a bit higher even, but, better to err on the side of underuse. I'd test the last print through the fixers for residual silver anyway, just for peace of mind.

Best,

Doremus

[angusparker]

Keep in mind that there are different standards of acceptable dissolved silver in fixers for film and for paper. Film fixer can have a lot more silver in it and still do the job just fine. However, you don't need fancy test strips for film fixer; just do a clip test and keep track of clearing times. Toss the film fix when clearing time for a particular film is 2x that in fresh fix.

For fiber-base prints, the whole situation is more complicated. If you want archival permanence, use two-bath fixing and toss the first fix before its throughput capacity has been reached. This keeps the second bath fresh. You can also use a single-bath regime, just remember that the fixer capacity is kind of low (10 8x10s per liter or fewer). Test for residual silver/hypo too to check your process. Even these tests won't tell the whole story. It's best to "underuse" the fix and be sure.

Angus, I imagine that using the first print fix to 1.5g dissolved silver and then changing out would be a good starting point. You might be able to go a bit higher even, but, better to err on the side of underuse. I'd test the last print through the fixers for residual silver anyway, just for peace of mind.

Best,

Doremus

I've made myself a fancy laminated sheet with checkboxes that after I have completed each set of boxes should mean the fix is spent. A sheet of 4x5 = 0.25 of a check, 120 = 1, 8x10 = 1, 11x14 =2 and 14x17 = 3 units and so on - following the manufacturers guidelines on film fixing. I'll back this up with the occasional check closer to the end to see what the dissolved Ag is.

[Doremus Scudder]

I've made myself a fancy laminated sheet with checkboxes that after I have completed each set of boxes should mean the fix is spent. A sheet of 4x5 = 0.25 of a check, 120 = 1, 8x10 = 1, 11x14 =2 and 14x17 = 3 units and so on - following the manufacturers guidelines on film fixing. I'll back this up with the occasional check closer to the end to see what the dissolved Ag is.

Angus,

At the risk of sounding like a broken record, let me stress again that the best way to test film fixer for exhaustion is with a clip test for clearing time. Sure, keeping track of throughput is a good idea but the clip test is more accurate as it tests the fix itself. Throughput assumes average density for all negatives; your fixer will exhaust faster more thin negs are run through it... Additionally, allowable dissolved silver content is much higher for film fixers than for print fixers. Consult the Ilford fact sheet I linked to earlier for more exact info. Do not use fixer used for film for prints. The by-products from fixing film will negatively affect the paper fixing process.

The advice I've given you above is mainly for fixing fiber-base prints. This is the critical step and where the dissolved silver must be kept very low for archival permanence.

Best,

Doremus

[Pere Casals]

Useful advice, I'll follow it.

[Tin Can]

Doremus,

Good to know I already follow best practice. I do use different batches of fix for film and paper. Even 2 different formulae to eliminate confusion.

I do a clip test before every usage of either fixer with strips of left over X-Ray film cuttings.

I also count footage as Angus does.

The ag/ph test strips aren't expensive and confirm my methods.

I still consider myself a novice and an old man with increasing brain fade, repetitive confirmation is necessary. For me.

[angusparker]

Angus,

At the risk of sounding like a broken record, let me stress again that the best way to test film fixer for exhaustion is with a clip test for clearing time. Sure, keeping track of throughput is a good idea but the clip test is more accurate as it tests the fix itself. Throughput assumes average density for all negatives; your fixer will exhaust faster more thin negs are run through it... Additionally, allowable dissolved silver content is much higher for film fixers than for print fixers. Consult the Ilford fact sheet I linked to earlier for more exact info. Do not use fixer used for film for prints. The by-products from fixing film will negatively affect the paper fixing process.

The advice I've given you above is mainly for fixing fiber-base prints. This is the critical step and where the dissolved silver must be kept very low for archival permanence.

Best,

Doremus

Great advice. I have separate fix for film and paper. I'll end up doing both I think - check throughput to let me know when I'm in the ballpark and then the clip test / test strip.

[Doremus Scudder]

Great advice. I have separate fix for film and paper. I'll end up doing both I think - check throughput to let me know when I'm in the ballpark and then the clip test / test strip.

I notice that I'm still not as clear as I'd like to be. Just so there's no confusion and to summarize our results:

Separate fixers for film and prints.

Clip-test for film fix to determine exhaustion. When the clearing time reaches 2x that in fresh fix, discard the fixer.

Keeping track of throughput and two-bath fixing for fiber base prints. If you use the test strips, test the first bath and discard when dissolved silver reaches 1.5-2g/liter. Add to this tests for residual silver and hypo to confirm your workflow.

Best,

Doremus