[Alt-photo] HT-2 residual hypo test

`Richard Knoppow dickburk at ix.netcom.com
Sun Aug 6 16:09:02 UTC 2017


    This is a very old fashioned test. It has not been considered valid 
for silver-gelatin for decades.  The currently accepted test for hypo is 
a solution of silver nitrate preserved with some acid.
Kodak HT-2
Water........................750.0 ml
28% Acetic acid..............125.0 ml
Silver nitrate, crystals.......7.5 grams
Water to make..................1.0 liter
The water should be double distilled.
This is about a 100 year supply, better made up in smaller amounts.
To use: put a drop on an unexposed area of the film or paper and allow 
to stand for about 2 minutes. Then rinse or blot off. Any stain 
indicates residual thiosulfate. The approximate amount may be determined 
by comparing the stain with those on the Kodak Hypo Estimator. Film 
should be held against a sheet of white paper.
    The solution will keep about 6 months in a stoppered bottle kept 
away from light.
    There is a more precise version of this test that requires fixing 
the stain and measuring it on a densitometer. I don't have that at hand.

On 8/5/2017 10:46 AM, Gordon Holtslander via Alt-photo-process-list wrote:
> >From Facts and Formula's 
>
> HT-1a
>
> Distilled water 180cc
> Potassium permagnate 0.3 g
> Sodium hydroxide 0.6 g
> distilled water to make 250cc
>
> take 250cc of pure water in a clear glass and add 1 cc of test solution. Then take one 8x10" film or plate from the wash water and allo the water to drip for 30 seconds from its surface into the galss containing the test solution.
>
> If a small percentage of hype is present the violet color will change to orange in about 30 seconds. with larger concentrations of hype the orange color witll change to yellow.
>
> when no change in the violet color occurs this indicates that the hype content has been reduced to a safe margin.
>
> oxided organic matter in the water reacts and chnages the color in the same manner. test tap water alone and see if color changes, using same volume of water from paper. Note color change. If hypo from paper is present color will change more.
>
> Gordon J. Holtslander
> gjh at shaw.ca
> Learn about HSP http://sp-foundation.org
>
>
> From: "alt-photo-process-list at lists.altphotolist.org alt-photo-process-list at lists.altphotolist.org" <alt-photo-process-list at lists.altphotolist.org>
> To: "alt-photo-process-list at lists.altphotolist.org alt-photo-process-list at lists.altphotolist.org" <alt-photo-process-list at lists.altphotolist.org>
> Sent: Saturday, August 5, 2017 11:06:38 AM
> Subject: [Alt-photo] HT-2 residual hypo test
>
> All,
>
>
> I am looking for a test chart that Kodak used to sell with the HT-2 residual hypo test that quantifies the amount of thiosulfate in the paper. This was used in the B&W days to test for washing of the prints. I am trying to be more scientific about my salted paper printing.
>
> Does anybody have such a chart and could scan it for me.
>
>
> Marek
>
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-- 
Richard Knoppow
dickburk at ix.netcom.com
WB6KBL



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