Doremus Scudder
Member
Richard,
I guess I'm giving up trying to reason with you at this point. Your own posts demonstrate that you are confused about this. Although I haven't received my copy of "Creative Elements" yet, the excepts you posted lead me to believe that it and the literature from Kodak (and many other sources about this) do not contradict each other. I believe the misunderstanding lies with you. You seem to not be able or willing to see the difference between tests for adequate fixing (i.e., tests for residual silver) and tests for adequate washing (i.e, tests for residual hypo/thiosulfate compound). Nevertheless, they are two different things.
So for those who are following this thread and those who will read it in the future, I'd like to prevent misinformation from spreading and emphatically make the distinction:
There are separate tests for adequate fixing and adequate washing. Note that an inadequately-fixed print can be washed well and pass the washing test.
The Kodak HT-2 test is a test for residual hypo, i.e. a test for remaining thiosulfate compounds from the fixer that haven't washed out.
It is a test for adequate washing.
It uses silver nitrate as the test reagent. It leaves a stain on the tested area proportional to the amount of residual fixer compounds left in the paper/film being tested. Originally, it was sold together with a "Hypo Estimator," which was a comparison scale. Nowadays, you can find it for download on the Internet from various sites.
It is worth noting that there is an older Kodak test for washing, the HT-1a test, which uses potassium permanganate as a reagent. Kodak gives it in a 1944 book of formulas, but only mentions the HT-2 test in later publications. Steve Anchell's Darkroom Cookbook, 3rd. ed. gives this formula, but not HT-2. This is also likely the same test R.Gould mentions in his posts above from his 1935 source.
The Kodak ST-1 test and the sodium-sulfide test that Ilford describes in their literature are identical, and is a test for residual silver.
It is a test for adequate fixing.
It uses sodium sulfide as a test reagent. It, too leaves a stain on the tested area, but this time in proportion to the amount of residual silver compounds in the print/film that have not been adequately fixed. Any stain other than a very faint cream-colored stain indicates improper fixation. Note that this test needs to be done on a well-washed print, but that washing is not what is being tested.
The test using Kodak Rapid Selenium Toner is an alternative test for residual silver and can be used in place of ST-1. It uses selenium as a test reagent.
It, too, is a test for adequate fixing.
And, it too leaves a stain on the tested area proportional to the amount of residual, inadequately-fixed, silver compounds in the print/film tested. Many (myself included) prefer this test to the ST-1 test since the test solution lasts much longer and it doesn't stain things as readily as silver nitrate.
Formulas and instructions for use for the above are available in the Kodak document I linked to above and from numerous other sources on the Internet and in print. Anchell's Darkroom Cookbook, 3rd ed. gives both the ST-1 and selenium toner tests for residual silver.
Best,
Doremus
I guess I'm giving up trying to reason with you at this point. Your own posts demonstrate that you are confused about this. Although I haven't received my copy of "Creative Elements" yet, the excepts you posted lead me to believe that it and the literature from Kodak (and many other sources about this) do not contradict each other. I believe the misunderstanding lies with you. You seem to not be able or willing to see the difference between tests for adequate fixing (i.e., tests for residual silver) and tests for adequate washing (i.e, tests for residual hypo/thiosulfate compound). Nevertheless, they are two different things.
So for those who are following this thread and those who will read it in the future, I'd like to prevent misinformation from spreading and emphatically make the distinction:
There are separate tests for adequate fixing and adequate washing. Note that an inadequately-fixed print can be washed well and pass the washing test.
The Kodak HT-2 test is a test for residual hypo, i.e. a test for remaining thiosulfate compounds from the fixer that haven't washed out.
It is a test for adequate washing.
It uses silver nitrate as the test reagent. It leaves a stain on the tested area proportional to the amount of residual fixer compounds left in the paper/film being tested. Originally, it was sold together with a "Hypo Estimator," which was a comparison scale. Nowadays, you can find it for download on the Internet from various sites.
It is worth noting that there is an older Kodak test for washing, the HT-1a test, which uses potassium permanganate as a reagent. Kodak gives it in a 1944 book of formulas, but only mentions the HT-2 test in later publications. Steve Anchell's Darkroom Cookbook, 3rd. ed. gives this formula, but not HT-2. This is also likely the same test R.Gould mentions in his posts above from his 1935 source.
The Kodak ST-1 test and the sodium-sulfide test that Ilford describes in their literature are identical, and is a test for residual silver.
It is a test for adequate fixing.
It uses sodium sulfide as a test reagent. It, too leaves a stain on the tested area, but this time in proportion to the amount of residual silver compounds in the print/film that have not been adequately fixed. Any stain other than a very faint cream-colored stain indicates improper fixation. Note that this test needs to be done on a well-washed print, but that washing is not what is being tested.
The test using Kodak Rapid Selenium Toner is an alternative test for residual silver and can be used in place of ST-1. It uses selenium as a test reagent.
It, too, is a test for adequate fixing.
And, it too leaves a stain on the tested area proportional to the amount of residual, inadequately-fixed, silver compounds in the print/film tested. Many (myself included) prefer this test to the ST-1 test since the test solution lasts much longer and it doesn't stain things as readily as silver nitrate.
Formulas and instructions for use for the above are available in the Kodak document I linked to above and from numerous other sources on the Internet and in print. Anchell's Darkroom Cookbook, 3rd ed. gives both the ST-1 and selenium toner tests for residual silver.
Best,
Doremus