Dear Bob, thank you for mentioning the role of ammonium ions in dealing
with the silver-thiosulfate complexes, hence the two fixing bath regime
(which to some is not needed when a rapid fix is used for the very reason).
Thanks Jean-David for the formula provided - do you happen to know the pH?
V V sre., 6. nov. 2019 ob 13:13 je oseba Jean-David Beyer <
dmarc-noreply@xxxxxxxxxxxxx> napisala:
On 11/6/19 6:27 AM, Miha Golobic wrote:
Recently I have been playing with the idea of using powdered chemicals
only. Developer is of no concern to me, however fixer is another matter
(so they say!). Fot too many times a message came across from many
experts and "experts" advocating that with today's materials ammonium
based fixer is a must and that sodium fixer can produce less than
permanent images. Is that really the case? Kodak, Foma, Tetenal (as well
as Formulary, etc) offer such without reservations. I would really like
to know if anyone has tested modern papers fixed with sodium fixer for
residual silver?
I do not know if something like Kodak Rapid Fixer is better than regular
Kodak Fixer or not. But if you want to make a rapid fixer using dry
chemicals, consider Kodak F-7
water (50C) 600 ml
Sodium thiosulphate (pentahydrated) 360 gram
Ammonium chloride 60 gram
Sodium sulphite (anhydrous) 15 gram
Acetic acid (28%) 48 ml
Boric acid crystals 7.5 gram
Potassium Alum fine crystals dodecahydrated 15 gram
Cold water to 1000 ml
F-9 is the same, but use 60 gram ammonium sulfate instead of 50 gram
ammonium chloride. Reduces corrosion of stainless steel.
If you do not need or want hardener, leave out the Potassium alum.
I do not know what to use instead of acetic acid.
These are faster than normal F-5 or F-6 fixers, but not as fast as Kodak
Rapid Fixer (liquid).
--
.~. Jean-David Beyer
/V\ PGP-Key:166D840A 0C610C8B
/( )\ Shrewsbury, New Jersey
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