There are tests for retained fixer (hypo) so you don't have to wait.
Originally Posted by SchwinnParamount
Short of testing for retained hypo, I think I'd want to wait considerably longer than five years to have any kind of certainty. If something is visibly failing in just five years, the processing is not just bad, it's awful.
Originally Posted by SchwinnParamount
But in one respect you are right to ask. I take it on faith that all your basic wash aid products are based on sodium sulfite or ammonium sulfite, and that they all do about the same job, and that the original research on sulfite based washing aids was accurate. You don't have to. I haven't the expertise to do an analytical chemistry analysis of Permawash, Clayton's or Lauder's wash aids, Orbit Bath, and the like. But if what I've read is here and other places to be believed, they're all sulfite based wash aids. And if the original research is to be believed, they all do about the same thing.
Personally, I tend to wash more than the minimum recommendations anyway, just to be sure.
Hypo clearing agents exist primarily for the purpose
of breaking the bonds twixt fixers and the cellulose and
the baryta coatings of FB paper. Little to nothing is to be
gained by using the agents with film or RC papers.
Advised are a very few rinses with some agitation and
an increase in time with each rinse cycle. If working
with FB paper add to that a HCA. Dan
Are the tests uniformly reliable? Is a test kit made by one manufacturer any more foolproof than another?
Originally Posted by hrst
The HT-2 test is the at home test for residual hypo.
The Ilford version is nothing more than a 1% solution
of silver nitrate. The silver will combine with any
remaining sulfur producing a stain. The test is
conducted drop wise. Very little of the test
solution will go a long ways.
If interested I can detail the method for using
the HT-2 test. Dan
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dancqu, I would be interested in the details of the Ilford test if the application differs from Kodak's. Can you post them here? Is Kodak's acetic pretty much a optional add on?
For others, below is the HT-2 test
Kodak Hypo Test HT-2 residual hypo test
Distilled Water . . . . . . . . . . . . . . . . . 750 ml
28% Acetic Acid . . . . . . . . . . . . . .* .125 ml
Silver Nitrate, Crystals . . . . . . . . . . . . 7.5 g
Distilled Water to Make . . . . . . . . . . .* * 1 L
Silver nitrate takes around 24 hours to fully dissolve.
(Store in a tightly sealed brown glass bottle away from strong light sources.* This solution stains everything it touches, so don’t splash it around.)
For paper, place one drop on the border of the print, let it stand for 2 minutes, then rinse with water.* If the print is thoroughly washed the solution will produce only a very faint tea-colored stain, or possibly no stain at all.* If it is inadequately washed, the solution will produce a rather dark tea-colored stain. To judge the stains accurately you should purchase a Kodak® Hypo Estimator, which costs about $3.
For film, cut off a small piece of film and drop it into the test solution for 3 minutes.* Properly washed films should show virtually no discoloration.
And, the retained Silver test is very immediate and obvious. It is a solution of Na2S (Sodium Sulfide) in water. One drop on an improperly fixed print turns black or brown instantly.
Or alternatively, proposed by Kodak, a 1+9 solution of KRST. The good thing about it is that it has much better shelf life than Na2S solutions. Only a drop is needed to prove if film/paper has been properly fixed. Film that has only cleared will give obvious stain. Likewise, improperly fixed paper will stain, but don't let the drop for more than 2-3 minutes, as leaving it for far too long will stain it anyway.
Originally Posted by Photo Engineer
I use Na2S due to the greater toxicity of Se over S, but yes both are usable.
Yes, an optional add on. The acetic version is less sensitive to
Originally Posted by CBG
light and the drop spots on paper do not discolor so much over
time. Otherwise the two yield the same results.
I test my wash method by scattering one or two drop measures
about a sheet of paper. With safe lights on the measures are
placed at half minute intervals and after 3 minutes blotted
up in succession. A night light is used for evaluation.
The acetic version leaves more time for evaluation but
IMO the Ilford version allows enough.
A gram of silver nitrate for 100ml of test solution
will last and last and ... Zero stain is good
enough for me. Dan