[pure-silver] Re: Hypo Test Sensitivity

Richard

That was my understanding too, but the HT1 test seem to be well and alive in
Continental Europe. It is preferred to HT2 and according to German amateur
literature, far more sensitive than the silver-nitrate test. Amaloco, a
Dutch manufacturer of photographic chemicals, sells a version of HT1, called
H15. As far as I know, only SilverPrint in London still sells a version of
HT2.

I'm currently investigating the differences.

According to Levington (1957?) and Haist (1979?), equilibrium, during
diffusion washing, is reached within 5 minutes or so. That's the foundation
of the Ilford Washing Technique. If that is so, hypo is not bound to the
emulsion, and HT1 is a valid test (true?). According to Amaloco, H15 is
sensitive down to 0.001 g/l hypo. That's roughly 100x more sensitive than
HT2, which goes down to about 1 µg/m^2. This comparison is admittedly
assumes equilibrium with the surrounding wash water again.

Unfortunately, I know nothing about the methylene-blue test, but a test, not
practical for 'the rest of us', is only of academic interest to me anyway.
That's why I'm concentrating on the comparison of HT1 vs HT2.

Who knows more about the pro and cons of HT1 vs HT2?





Regards



Ralph W. Lambrecht

http://www.darkroomagic.com







On 2006-06-28 03:46, "Richard Knoppow" <dickburk@xxxxxxxxxxxxx> wrote:

> 
> ----- Original Message -----
> From: "Ralph W. Lambrecht" <info@xxxxxxxxxxxxxxxx>
> To: "PureSilverNew" <pure-silver@xxxxxxxxxxxxx>
> Sent: Tuesday, June 27, 2006 4:43 PM
> Subject: [pure-silver] Hypo Test Sensitivity
> 
> 
>> I'm trying to compare the test sensitivities of HT1 vs
>> HT2. HT1 measures the
>> residual hypo content of the last wash water using
>> potassium permanganate,
>> and HT2 measure the residual hypo content of the emulsion
>> using silver
>> nitrate.
>> 
>> Has anyone used both and can share their experience?
>> 
>> 
>> 
>> 
>> 
>> Regards
>> 
>> 
>> 
>> Ralph W. Lambrecht
>> 
>> http://www.darkroomagic.com
>> 
>> 
>     The permanganate test has been obsolete for decades. I
> measures the amount of hypo in water dripping of a print or
> film. Since hypo may be bound to the emulsion or the paper
> the test is very imcomplete. the Silver Nitrate test is
> better since it test for hypo actually in the emulsion or
> support. The Methyelene blue test is supposed to be even
> more accurate but its not very simple.
> 
> ---
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@xxxxxxxxxxxxx
> 
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