[pure-silver] Re: Edwal Hypo Test and Poor memory
- From: Eric Nelson <emanmb@xxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Mon, 10 Jan 2011 17:06:10 -0800 (PST)
Thanks John that's what I remember or thought I did...
I realize Richard that Edwal H√ might be inaccurate but since I'm in there at
least 5 days a week lately, I just need something that gets me in the ball
park.
Since I use 2 baths I won't sweat it too much as I mostly need to get an idea
of when to dump that first bath but thanks for the info.
e
________________________________
From: John Meyers <jmeyers102@xxxxxxxxx>
To: pure-silver@xxxxxxxxxxxxx
Sent: Mon, January 10, 2011 5:55:34 PM
Subject: [pure-silver] Re: Edwal Hypo Test and Poor memory
I wouldn't doubt that Richard is correct about Edwal Hypo-Chek not being a
reliable test. But to answer your question, below are the instructions from my
bottle of Hypo-Chek:
FOR HYPO FIXERS: Add 2 drops Hypo-Chek. If a white precipitate forms, discard
the fixer.
FOR HIGH SPEED FIXERS: Dip out 1 or 2 ounces of the fixer. Add 1 or 2 drops of
Hypo-Chek and shake. When a permanent milkiness remains, the fixer should be
discarded. Hypo-Chek will not harm any fixing bath.
John Meyers
--- On Mon, 1/10/11, Richard Knoppow <dickburk@xxxxxxxxxxxxx> wrote:
>From: Richard Knoppow <dickburk@xxxxxxxxxxxxx>
>Subject: [pure-silver] Re: Edwal Hypo Test and Poor memory
>To: pure-silver@xxxxxxxxxxxxx
>Date: Monday, January 10, 2011, 5:52 PM
>
>
>
>----- Original Message ----- From: "Eric Nelson" <emanmb@xxxxxxxxx>
>To: "pure silver" <pure-silver@xxxxxxxxxxxxx>
>Sent: Monday, January 10, 2011 10:56 AM
>Subject: [pure-silver] Edwal Hypo Test and Poor memory
>
>
>> My bottle of Edwal hypo check test's instructions on the bottle are worn off
>>and
>> as I remember the instruction for testing paper rapid fixer was to add a
>couple
>> drops to an ounce or so, (I used 10-20 mls in a graduated cylinder) and
>> swirl the mixture. If the milkiness disappears, then it's still good.
>>
>> Can anyone confirm this from their bottle or experience? Just want to make
>>sure
>> my memory isn't completely awol.
>>
>> Thanks
>> Eric
>>
>>
> My bottle of HypoCheck is not available at the moment but its not a
> reliable
>test anyway. Hypo Check is a solution of iodide and forms silver iodide when
>added to the hypo. The problem is that the reaction depends on the
>consentration
>of the solution and, in any case, its not very sensitive. Kodak has a formula
>for a similar test solution in the _Black and White Darkroom Dataguide_ and
>elsewhere.
> A much better test for the fixer is to fix out a scrap of paper or film
> and
>use the residual silver test published by Kodak. If the sample is washed
>before
>testing you can use a 1:9 dilution of Kodak Rapid Selenium Toner rather than
>the
>sodium sulfide solution in the published formula. The KRST test fails if there
>is a lot of hypo in the emulsion so it should be washed, at least briefly. If
>the fixer is working the test should produce NO stain. Its used on wet but
>blotted emulsion. Place a drop on a clear area and allow it to stand for about
>one minute, then blot off. There should be no visible stain. If used on a
>print
>wash the print as you would after toning because the residue of the toner will
>eventually cause a stain.
>
>Here are some formulas for test solutions:
>
>Kodak Fixer Test Solution FT-1
>Water (at about 80F or 27C) 750.0 ml
>Potassium iodide 190.0 grams
>Water to make 1.0 liter
>
>To test a single bath fixer. To 5 drops of test solution add 5 drops of fixing
>bath and 5 drops of water. Discard the fixer if a yellow-white precipitate
>forms
>instantly. Disregard any slight milkiness.
> The instructions for two bath fixers do not make sense and I think the
>dilutions are reversed. They recommend testing the first bath with the same
>dilution as a single bath but a greater dilution for the second bath. Since
>the
>sensitivity of the test decreases with dilution I think this is opposite of
>the
>correct practice. Kodak recommends taking 5 drops of solution, 5 drops of
>fixer,
>and 15 drops of water for the second bath. I think probably this applies to
>the
>_first_ bath and it is the second that is tested the same as the single bath.
>In
>any case the dilution is known where it is not for the Edwal test.
> Also a liter of this stuff is a lifetime supply for an army. Probably
> around
>100ml is a more sensible amount.
>
>Residual Silver Test ST-1
>Water 100.0 ml
>Sodium sulfide, anhydrous 2.0 grams
>
>Store in a small stoppered bottle for no more than 3 months.
>For use dilute one part of the above stock solution with 9 parts water. The
>diluted solution should be replaced weekly.
> To use place a drop on a clear area of the print or film and allow to stand
>for 2 to 3 minutes. Blot off with a clean, white blotter. There should be no
>stain. Any stainging indicates residual silver halide. Note that the spot will
>stain with time so the test should be made on a scrap of paper processed with
>the prints or on a clear border of negatives.
>
> The KRST test mentioned above is as effective and has no odor but will fail
>to show a stain if there is much hypo in the emulsion.
>
>Residual hypo test, a test for completeness of washing.
>
>Residual Hypo Test Solution HT-2
>Water 750.0 ml
>28% Acetic acid 125.0 ml
>Silver nitrate crystals 7.5 grams
>Water to make 1.0 liter
>
>Note, use distilled water. Chlorine in the water will combine with the silver
>to
>form a precipitate of Silver chloride.
>Store the solution in a screw-cap or glass-stoppered brown bottle away from
>strong light at 65F to 75F (18C to 25C); it will keep for about 6 months
> Apply a drop fo the solution to a clear, unepsoed area of the emulsioni
> sid
>eof processed film that has been squeegeed or sponged. Allow it to stand for
>about 2 minutes. Then rinse off the testg olution with water, blot the excess
>water. The instructions are than to compare any stain to the examples printed
>in
>the book. Kodak also made an estimation strip with example stains. Some
>materials will show more stain than others but there should not ever be a
>stong
>stain. As with the other tests this one will generate a dark stain with time.
>There is a more sophisticated version of this test where the stain is fixed
>with
>salt, it can then be compared for density using a densitometer and prepared
>examples. The methylene blue test currently specified by the ISO is more
>sensitive for quantitative testing but is too complex for routine tests and
>this
>one works well enough for routine darkroom use.
> To test the effectiveness of a washer entire prints should be fixed out,
>washed, and immersed in the test. It will show if the washer is uneven in its
>effectiveness.
>
>
>--
>Richard Knoppow
>Los Angeles
>WB6KBL
>dickburk@xxxxxxxxxxxxx
>=============================================================================================================
>
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