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Re: [BKARTS] Sodium Borohydride for Bleaching



Jet,

I have a small tin  of NaBH4 containing a bottle (100g) bought some 20 years ago as a
result of reading Dr Hey's article on "Paper Bleaching" in The Paper Conservator, Vol.2,
1977.  She describes a number of problems and supplies some references to it use.
The point is made in her paper that the substance hydrolyses to sodium hydroxide and
therefore should not be used on media susceptible to caustic alkalis, such as
manuscripts and coloured or pigmented materials.   Also the production of hydrogen
within the media weakens the structure.  A 1% solution of acetic acid is used to remove
residual sodium salts.

The tin label contains a warning that once opened moisture may cause hydrogen to
evolve.   The same warning is on the bottle contained within the tin.   The powder in
side is not now free running and seems to be fairly solid, but presumably if extracted
with a spatula would still dissolve in water.   Clearly the bottle should opened in a dry
atmosphere and for a short a time as possible presumably.

In the end I decided to use calcium hypochlorite and calcium hydroxide for deacidfying
and bleaching since then, as described in her paper, as the most straightforward and
least problematic of the methods - for me at any rate working at home!  The use of the
calcium hypochlorite requires the weak acetic acid treatment in any case.


Rodney Fry
Crowthorne
England


On 11 Jan 2005 at 0:00, Automatic Digest Processor wrote:

   Does anyone on this list have experience with using sodium
borohydride?  The reference "Bookbinding and the Conservation of Books,"
(Library of Congress) states that it is one of the most effective agents
in combatting foxing in books.  The Rohm and Haas (the principal
manufacturer in the US) website touts its safety.  Yet, the MSDS sheet
......................................................................

Before I order any of this stuff,  I would like to know what I'm
getting into.
Thanks and best wishes,
Jet



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