mark (mark@argenta.freeserve.co.uk)
Sun, 25 Jul 1999 21:56:54 +0100
Method No 1 came from the book “Inorganic & Physical Chemistry”. And
according to the Dictionary of Photography, method No 2, was a Kodak patent
specification, “Kodalk”.
You say why go to the trouble of making it? Well I have a good supply of sod
hydroxide and borax, and if its possible for me to compound my own chems, I
will do so. Another factor for me to consider is the cost. Whenever I find
the need to make up a ‘new’ compound, I always consider the possible
dangers, and consult reference books upon the subject. It’s just basic
common sense. But then, why go to the time consuming trouble of making your
own silver bromide emulsion? Why spend hours preparing and making Kallitype’
s, when you can go to the shop and buy a box of photo paper?
Mark.
-----Original Message-----
From: Sil Horwitz <silh@iag.net>
To: alt-photo-process-l@sask.usask.ca <alt-photo-process-l@sask.usask.ca>
Date: Sunday, July 25, 1999 7:47 PM
Subject: Re: sodium metaborate, to make?
At 1999/07/25 07:01 PM +0100, mark wrote:
>I need to make up a small amount of sodium metaborate “Kodalk”, and came
>across two possible methods of doing so.
>
>Method 1
>Add 40gms of sodium hydroxide to a solution of 20gms borax.
>
>Method 2
>Fuse together 20parts of borax and 4.2parts of sodium hydroxide.
>
>Anyone know which method is correct?
Commercially, sodium metaborate is made by fusing equivalent molecular
weights
of borax and sodium carbonate. Personally, I never heard of the sodium
hydroxide method. And certainly just adding the two solutions would give a
whole range of borate compounds. If you do plan to fuse, it's good to
remember
two things: (1) melting point is 966 C, and (2) gases are evolved during the
process.
But - as sodium metaborate is so readily available, why would you want to go
to
the trouble of making it at greater expense?
Sil Horwitz, FPSA
Technical Editor, PSA Journal
silh@iag.net
silh@earthlink.net
Visit http://www.psa-photo.org/
Personal page: http://home.earthlink.net/~silh/
This archive was generated by hypermail 2.0b3 on Thu Oct 28 1999 - 21:40:38