Hi,
30 grams of silver nitrate is $34.00 from Artcraft, the place to get
your mix.
Rich
On Fri, May 6, 2016 at 4:46 PM, `Richard Knoppow <dickburk@xxxxxxxxxxxxx>
wrote:
There are two tests for hypo, one is a test of the fixing bath to
determine the amount of silver dissolved in it, the other is a test of
fixed emulsion to see how much residual silver halide is in it. The first
is not a very good test because it does not really show how effective the
hypo is, the second is the one to use to see if film or prints are
completely fixed. Here are both:
Kodak Residual Silver Test Solution ST-1
Stock Solution
Water.........................100.0 ml
Sodium sulfide (not sulfite)....2.0 grams
To use dilute stock solution 1 part with 9 parts water.
To use place 2 or 3 drops of working solution on a clear area of the film
or an unexposed but processed section of paper. Allow to sit for about 3
minutes and blot off with a clean blotter. If fully fixed there will not no
more than a very slight cream stain.
Note that after a time the test area will develop a permanent stain so
tests should be made on a margin of a negative or on a small piece of paper
which has not been exposed but has been processed along with the prints.
This test is for residual silver halide or fixer reaction products in
the emulsion.
A more stable test solution can be made using Kodak Rapid Selenium
Toner diluted 1 part toner to 9 parts water (as a working solution).
However, this test will fail if there is a large excess of hypo remaining
in the paper.
Life of the stock solution is not more than 3 months.
Life of the working solution is not over a week.
Note, there is another test, which I will post later that leaves a
cloud in the fixing bath when there is excessive amount of dissolved silver
in it. However, the above is a direct and much more reliable test of the
effectiveness of the fixing process.
Testing for residual hypo:
Water....................................750.0 ml
Acetic Acid, 28%.........................125.0 ml
Silver Nitrate.............................7.5 grams
Water to make..............................1.0 liter
Store in screw top or glass stoppered brown bottle. Keep away from light.
Avoid contact with the test solution because it will cause black stains
which are very difficult to remove.
To use: After washing wipe excess moisture from surface of film or paper.
Place one drop of the solution in a clear area on the border of the film or
on a piece of printing paper which was processed with the prints. Leave
the solution in place for 2 minutes and rinse to remove excess test
solution. Then compare any stain with the color patches on the Kodak Hypo
Estimator. The estimator is found in many Kodak Darkroom Data Guides.
However, the stain should not be more than a very slight brown eggshell
color, preferably there should be no stain. This solution will work with
Kodak Hypo Cleaing Agent but may give false results when used on prints
treated in Kodak HE-1 Hypo Eliminator. The solution should not be used on
wet films because the spot may spread out, however it is useful for dry
film. Film can also be tested by cutting off a small clear area of the
negative and immersing it in the solution for three minutes. Rinse off.
There should be little or no coloration.
There is a more elaborate version of this test which gives
quantitative measurements of hypo content. It requires complete immersion
of the test material and a method of stabilizing the stain. This the
density is measured with a densitometer. I don't have the reference
available at the moment but can find it. It is not necessary to go beyond
the simplified method above to test for effectiveness of washing.
If the solution being sold by Freestyle is of the second type its cost
may be dictated by the cost of the silver nitrate in it.
On 5/6/2016 2:29 PM, Tim Daneliuk wrote:
I happened to look at the current pricing for the PF Hypo-Test kit, I see
they are asking nearly $23 for this on Freestyle... this seems unreasonably
high. Moreover, they claim that it will not work with prints processed
with hypo eliminator, because it contains ammonium. Well ... so does Ilford
Rapid Fixer ... which I do use.
So, is there a reasonable, cheap alternative for hypo testing for prints
processed with an ammonium-based fixer?
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--
Richard Knoppowdickburk@xxxxxxxxxxxxx
WB6KBL
