[pure-silver] Re: Paraformaldehyde/Acetone in lith developers
- From: Claudio Bonavolta <claudio@xxxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Tue, 02 Mar 2010 14:36:24 +0100
----- Message d'origine -----
De: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
Date: Tue, 2 Mar 2010 02:41:34 -0800
Sujet: [pure-silver] Re: Paraformaldehyde/Acetone in lith developers
À: <pure-silver@xxxxxxxxxxxxx>
----- Original Message -----
From: "Robert Hall"
To:
Sent: Monday, March 01, 2010 9:46 PM
Subject: [pure-silver] Re: Paraformaldehyde/Acetone in lith
developers
> big snippy...
>
> Richard mentioned...
>
> Groceries used to carry Red Devil Lye, perfectly pure
> sodium hydroxide, and
> also 20 Mule-Team Borax, also pure enough for photographic
> uses. Both are
> useful in themselves but can be combined in solution to
> form "Kodalk" AKA
> sodium metaborate, pentahydrate (although Kodak called it
> octahydrate).
>
> You may not remember Richard, but i went out and bought
> 100 lbs of both
> because Kodalk is so expensive. I have been making my own
> for some time and
> it costs me 1/8th of what Kodalk would cost.
>
>
>
> Robert Hall
> www.RobertHall.com
I sort of remember it. I think it was Micheal Guzinowicz
who first mentioned that Kodalk could be made from sodium
hydroxide and borax. The first proportions were not quite
correct and were corrected by Ryuji Suzuki, I think. In any
case, for those not familiar with this sodium metaborate AKA
Kodalk can be made by adding sodium hydroxide to borax in
solution. The equivalent to 100 grams of Kodalk is equal to
45.45 grams of borax and 9.53 grams of sodium hydroxide.
Note the the Xtol patent refers to sodium metaborate
octahydrate whereas it is really the tetrahydrate which is
what is given by the above. The difference in the two
hydrations is really a matter of a difference in the
conventions of chemical notation, Kodak using an old
fashioned version. However, the stuff is the same. Kodak
began to issue a lot of formulas using Kodalk in the late
1930s because it had come up with a patented method of
producing the crystaline form cheaply. Metaborate has a pH
in-between borax and sodium carbonate. Like borax it does
not produce gas when acid is added and has relatively good
buffering although not as good as a combination buffer like
borax and boric acid.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
You're interesting me as I have some difficulties to find sodium metaborate but
have borax and sodium hydroxyde ...
What's the procedure ?
Do you really make sodium metaborate in crystalline form to re-use it later or
do you just mix the proportional quantities of both directly into the final
developer/fixer/... solution ?
So I went from commercial chemicals to mixing raw chemicals, and now I'm going
to make the raw chemicals ...
Anyone having the formula to change lead into gold ? :-)
Thanks,
Claudio
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