Have hypo check? Lock it up.

Stopped into the local photo shop and noticed that the small 3/4 oz dropper bottles of hypo check was $17.89. Yes, that's dollars not pesos.

So I checked B&H - $12.95. Adorama the same (though 4 oz bottle is $22). Freestyle more reasonable for their Arista brand - $4.49.

Apparently its a simple solution of potassium iodide and you can mix your own.

And handy to have around in case of a nuclear reactor accident.

Hypo-check is not really a good way to determine fixer exhaustion anyway... Save it for the nuclear holocaust and do residual silver tests on your prints to determine fixer capacity for your own workflow.

Best,

Doremus

Doremus is right. The test is rather subjective. Even the Kodak Hypo Test solution HT-2 for prints is subjective unless you have the color swatches for comparison in the Kodak B&W Darkroom Dataguide. Far better to just keep track of the number of films or prints passed through a bath.

Gerald C Koch said:

Doremus is right. The test is rather subjective. Even the Kodak Hypo Test solution HT-2 for prints is subjective unless you have the color swatches for comparison in the Kodak B&W Darkroom Dataguide. Far better to just keep track of the number of films or prints passed through a bath.

Click to expand...

Perhaps, but difficult to do in a community darkroom.

mgb74 said:

Perhaps, but difficult to do in a community darkroom.

Click to expand...

I always wondered:'could an ohmmeter help?since the resistance should go down with increasing silver content.Just a thought.

mgb74 said:

Perhaps, but difficult to do in a community darkroom.

Click to expand...

I was going to say the same. Hypo-chek is an important part of a large darkroom operation! With up to 18 students using two trays of fixer, counting equivilent of 8x10 sheets going thru would be awkward.

You bring up an interesting point, Vaughn. The problem is that once your Hypo-Check indicates exhaustion, you've likely been underfixing prints for some time... And it seems difficult to retroactively refix a bunch of prints from different people in a community or college darkroom. Maybe a two-bath fixing set-up with regular checks of the first bath with hypo-check would work better. When the first bath indicated exhausted, you could just mix up two fresh baths. That way, with the second bath staying much fresher than the first, you'd have a pretty good chance of never underfixing.

Best,

Doremus

RalphLambrecht said:

I always wondered:'could an ohmmeter help?since the resistance should go down with increasing silver content.Just a thought.

Click to expand...

A fixer solution is so concentrated that the addition of a proportionally few extra ions is not going to be noticeable. In addition, the stoichiometry of the silver complex is dependent on the total amount of silver. So, in any case, there would be no linear relationship between conductivity and silver content.

Sorry -- I spoke in the present tense. I retired last September! Our system worked fine for the 40 years I was associated with the darkroom. Most of the time there were maybe 3 or 4 people working (we had 75 to 80 hrs of open time per week) and the fixer was easy to keep track of. Only those who waited to print the night before the critiques had to deal with all 18 enlargers in use and the mad house that goes with that!

Why not just test the fixer throughout the print session? Mark a strip of paper with 1" increments under safelight; dip it in the fixer tray for, say, 15 or 30 secs. per inch. (so, four segments, you'll test the fixer for 15, 30, 45 and 60 seconds, with an unfixed section to hold onto). Room lights on and develop under room lights. Find the time that resulted in no staining and double it.

I've brought this up before, but - what is wrong with that methodology, which requires no extra chemicals and takes about 2 minutes during a session.

If I'm doing lith printing, I use a thin strip and put regular B&W developer in a small beaker. Really very convenient and you can see what specific papers need fix-wise. Am I missing something here?

That's like doing a test for fogged paper, only backwards!

I just bought a bottle for $7.69 locally. Maybe your bottle was mismarked and should have been $7.89 instead of $17.89. Or the store is just gouging you.

studiocarter said:

That's like doing a test for fogged paper, only backwards!

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Yes, to some extent - but my question remains - do you still need some sort of chemical test to ensure your fix is working, or is this sufficient?

BTW, the full process for me with fiber papers is to mark the test strip with time increments; soak in water for a minute or so (assuming here dry paper may respond differently than paper that has been dev'd and stopped); start the timer and fix for the desired increments; rinse the fix from the paper (20 secs. or so); room lights on; test strip into the developer.

A bonus to this test is if the unfixed portion of paper doesn't reach max black, the developer is exhausted. So you're actually checking 2 chems with one test.

In our community darkroom, we always run two fixer baths. When the first bath in the line shows it's dead when tested with hypo-check, it goes into the "dead fix" jug for recycling. The second bath moves into its place, and a fresh bath goes into bath #2's former place. It's impossible to track usage volume in our case.

pgomena said:

In our community darkroom, we always run two fixer baths. When the first bath in the line shows it's dead when tested with hypo-check, it goes into the "dead fix" jug for recycling. The second bath moves into its place, and a fresh bath goes into bath #2's former place. It's impossible to track usage volume in our case.

Click to expand...

This would be a good approach. Our darkroom is not continuously attended, so we also cannot track volume. And since it's just one part of a larger facility, without separate staffing, test strips are not very feasible.

We're thinking of using covered bus trays for stop and fixer. Their depth will allow a greater volume of fixer and the cover should add a little bit of life to the the solution.

Hypo check is good enough to tell me when to dump the hypo when I am printing. When I develop film it the film does not clear fast enough I change the hypo.

The problem of keeping fixer fresh and active in a community darkroom with no way to monitor throughput is interesting. There are a couple of possible workflows that come to mind.

Yes, you can use Hypo-Check for the first bath and toss it as soon as there is any sign of exhaustion. The problem with Hypo-Check is that it doesn't show exhaustion until the fixer contains significantly more than the 2g/l of dissolved silver that is the maximum for "commercial" or "general-purpose" photography and way higher than the 0.5g/l (or less, according to Haist) that is accepted for "optimum permanence." Using a second fixing bath will ameliorate this somewhat, but it, too, may reach higher than 0.5g/l if the first bath concentration gets too high... A second bath of greater volume would be a good safety factor, say a one liter bath one and a 1.5 liter bath two (or equivalent).

Using film clearing time on fixer used for prints should give better results than Hypo-Check; just do the clip test with a small amount of fixer drawn from the fixer tray (don't return it to the tray, but discard it after the test) and discard the fix when the clearing time doubles from fresh. This, in combination with two-bath fixing would likely be even better than using Hypo-Check.

The final thing is to test prints for residual silver on a regular basis. This is easy and a good check on your workflow as well as being the only really practical and reliable way to determine if you are fixing adequately. The common sulfide test (ST-1) is good, but a bit fiddly; easier and just as reliable is using selenium toner as a testing agent. I use a drop of straight KRST right out of the bottle to test my prints. leave the drop on an undeveloped area of the print for three minutes and then rinse. Any discoloration other than a very faint yellowing indicates underfixing. My prints show no discoloration at all. Test print borders regularly and every so often run a full sheet through the fix and test it in several locations (whenever I ruin a print under the enlarger by not stopping down, etc., the print goes right into the fix and gets used as a test sheet).

Regular testing will show if the fixing regime is working or not. If not, then adjustments can be made till a workflow that gives consistently good results is arrived at.

Best,

Doremus

Doremus Scudder said:

The problem of keeping fixer fresh and active in a community darkroom with no way to monitor throughput is interesting. There are a couple of possible workflows that come to mind.

Yes, you can use Hypo-Check for the first bath and toss it as soon as there is any sign of exhaustion. The problem with Hypo-Check is that it doesn't show exhaustion until the fixer contains significantly more than the 2g/l of dissolved silver that is the maximum for "commercial" or "general-purpose" photography and way higher than the 0.5g/l (or less, according to Haist) that is accepted for "optimum permanence." Using a second fixing bath will ameliorate this somewhat, but it, too, may reach higher than 0.5g/l if the first bath concentration gets too high... A second bath of greater volume would be a good safety factor, say a one liter bath one and a 1.5 liter bath two (or equivalent).

Using film clearing time on fixer used for prints should give better results than Hypo-Check; just do the clip test with a small amount of fixer drawn from the fixer tray (don't return it to the tray, but discard it after the test) and discard the fix when the clearing time doubles from fresh. This, in combination with two-bath fixing would likely be even better than using Hypo-Check...

Click to expand...

Which brings me back to the comments I've made on this thread... why not just use paper to test the fixer, after every x-number of prints, once an hour, whatever seems right?

If unexposed paper is fixed and developed, and comes out pure white, is that an accurate test of the fixer? Or is there some sort of invisible ghost of something that will biteyou over time?

I can see using film as a clearing test, but why test fixer with film when your intended use is paper? Why not test it on the paper you're using in that session? Wouldn't this eliminate the need for 2-bath fixing and allow you to find the exact fixing time needed, which would avoid overfixing and make washing easier?

Still wonder: what am I missing in using this workflow?

M Carter said:

... If unexposed paper is fixed and developed, and comes out pure white, is that an accurate test of the fixer? Or is there some sort of invisible ghost of something that will biteyou over time?

I can see using film as a clearing test, but why test fixer with film when your intended use is paper? Why not test it on the paper you're using in that session? Wouldn't this eliminate the need for 2-bath fixing and allow you to find the exact fixing time needed, which would avoid overfixing and make washing easier?

Still wonder: what am I missing in using this workflow?

Click to expand...

Developing underfixed paper won't show you if the fixer is exhausted. The problem is that the light-sensitive silver halides are first converted to insoluble compounds (which are then not sensitive to light) and then, as fixing progresses, converted to soluble ones. Exhausted fixer doesn't do the second step well and leaves insoluble compounds behind. These, however have been rendered non-light sensitive and will therefore not develop out; nor will they wash out, since they are insoluble.

However, your idea is good; run a control strip through the fixer every so often and test it for residual silver. The test using selenium toner I described above is really easy and could be done once an hour or whatever no problem. You would have to wash the control strip well first though. If you just use the control strip to test just the first bath, then you should be able to catch when it goes bad and when to replace it before the second bath stops doing its job and not have to worry about refixing. I'd test finished prints or control strips as well just to verify this, however.

The reason for suggesting film and doing a clearing test is that film is much easier to do this with than paper. You can't see when the paper clears due to the white base. A residual silver test is easier.

Best,

Doremus

Vaughn said:

Sorry -- I spoke in the present tense. I retired last September! Our system worked fine for the 40 years I was associated with the darkroom. Most of the time there were maybe 3 or 4 people working (we had 75 to 80 hrs of open time per week) and the fixer was easy to keep track of. Only those who waited to print the night before the critiques had to deal with all 18 enlargers in use and the mad house that goes with that!

Click to expand...

Nothing on-topic to add here. Just wanted to quietly nod and smile from afar at how great it is to be able to listen in on conversations like this. I graduated 2001 and, boy, what a treat it would be to see 18 people dialing in their prints like you recall, Vaughn.