Sil Horwitz (silh@iag.net)
Sun, 25 Jul 1999 14:40:41 -0400
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/
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