2x5 min seems on the long side to me, however with your extensive
instructions I may test it in the near future to be on the safe side.
Thank you again for your time.
Miha
V V čet., 7. nov. 2019 ob 23:06 je oseba `Richard Knoppow <
dickburk@xxxxxxxxxxxxx> napisala:
I am not sure how long the fixing for fiber paper should
take. It takes longer than for RC paper because some of the
emulsion gets into the baryta layer so the fixer must penetrate
it. The fixing times are shorter than those recommended in the
old books because they took into account the hardening action.
Not needed for modern papers. I would give fiber something like
five minutes in each bath. Then rinse or short wash, then hypo
clear, then wash as you have been doing, Kodak recommends 10
minutes for single weight, 20 minutes for double weight and 30
minutes for premium weight. This should be in a washer that
provides a continuous flow of water.
There is a test for residual hypo that uses a solution of
silver nitrate. Kodak HT-2. If there is much hypo it leaves a
permanent stain. There is another test for excess silver, Kodak
ST-1, in the emulsion, a weak solution of sodium sulfide. The
sulfide stains the halide as well as the metallic silver. It
leaves a yellow or brown stain similar to the hypo test. There
are more elaborate tests that give quantitative accuracy but they
are much more complex and the above simple tests are good enough
to confirm the fixing and washing process.
There is another test for the amount of silver dissolved in
the hypo, Kodak FT-1, using Potassium iodide. However, the amount
of silver in the fixing baths depends on whether a single or two
bath fixer is used and to some degree on whether a hypo clearing
agent is used (increases the allowable amount of silver.
I am posting the formulae and instructions:
Kodak FT-1 Fixer Test Solution
Water (at 80F or 27C)..........750.0 mL
Potassium iodide...............190.0 grams
Water to make....................1.0 Liter
For a single bath or the first bath of a two bath system take 5
drops of FT-1 add 5 drops of fixing bath and 5 drops of water.
Discard if a yellow-white cloud forms instantly.
For the second bath of a two bath system take 5 drops of
FT-1, add 5 drops of fixing bath and add 15 drops of water.
ST-1 can also be used to test film for excess silver. Dilute
the stock with nine parts water. Place a drop on a clear part of
the emulsion and allow to sit for 2 or 3 minutes. Then blot off.
Any yellow stain is an indication of too much silver left in the
emulsion.
Kodak HT-2 Hypo Test Solution
Water..............750.0 mL
Acetic acid, 28%...125.0 mL
Silver nitrate...... 7.5ml
Water to make........1.0 Liter
Use distilled water. Any impurities can cause the silver
nitrate to come out of solution.
A few drops of the solution should be placed in a clear area
of the image and allowed to stand for two minutes. It should
leave either a slight yellow stain or no stain. The stain is
permanent so the test is best done on a scrap processed with the
prints made.
Because silver nitrate is expensive you can make up a
fraction of this formula. This solution will keep about 6 months
in the dark.
I think these tests are a bit of overkill although the fixer
test can be useful in keeping track of how much the fixing bath
has been used.
On 11/7/2019 11:56 AM, Miha Golobic wrote:
Great, thank you. So for FB paper 2-3 min in each bath (sodium
fix no hardener), followed by 5 min wash, hypo clear, followed by
30-40 min wash (or water exchange) sounds about right as well.
So far my regime was 1-2 min in Ilford Hypam 1+4, single bath, no
hypo clear, wash up to 1 hour.
V sre., 6. nov. 2019 20:59 je oseba `Richard Knoppow
<dickburk@xxxxxxxxxxxxx <mailto:dickburk@xxxxxxxxxxxxx>> napisala:
--
Richard Knoppow
dickburk@xxxxxxxxxxxxx
WB6KBL
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