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Re: [BKARTS] sodium borohydride, too!



Well, here's the usual debate on bleaching cropping up.  In the
conservation community, Chloramine-T is virtually non-existent now.
Items bleached by it will continue to suffer long after you think you've
washed it all out.  There are of course anti-chlors which can be used in
the rinsing, etc.etc.  If there's a fuss, I'll track down some lab
reports about problems associated with it and give references.
Sodium borohydride is a reducing bleach, and used in concentrations of
about 0.5% up to 1.5% or so v/v in water.  It will often work
effectively on stains where oxidizing bleaches cannot.  It is safe to
use under the usual precautions- with ventilation, gloves, etc.  It is
mixed with water to create the bleaching solutions and will not
spontaneously ignite or explode in these concentrations.  It does
liberate hydrogen, so you will notice bubbles forming in the beaker as
you mix with water.  This can be a problem (as Jack Thompson alluded
to)- in some papers the efflorescence will cause blistering to occur on
the surface.

I'm risking suffering the wrath of people on the list, but MSDS sheets
are generally designed for industrial uses.  One must learn to
understand the data stated and not just jump to conclusions.

Don't throw the whole jar of NaBH4 in water and you should be fine.
Measure a small amount from the jar, and then add this to your water-
don't just shake the jar over a water bath. Use plastic/glass measuring
utensils.  We store ours tightly sealed in the fridge here and there's
no trouble.

Bleaching foxing stains can be tricky and difficult- due to the many
causes of foxing formation, one sort of bleach will work where another
will not.

Regards
Douglas Sanders
Senior Conservator
Indiana Historical Society
450 West Ohio Street
Indianapolis, IN 46202-3269
tel: 317-234-0045
dsanders@xxxxxxxxxxxxxxxxxx


> -----Original Message-----
> From: Edward Stansell [mailto:craftbookbinding@xxxxxxxxx]
> Sent: Tuesday, January 11, 2005 1:17 PM
> To: BOOK_ARTS-L@xxxxxxxxxxxxxxxx
> Subject: Re: sodium borohydride, too!
> 
> Jet,
> 
> Again, a very dangerous chemical. This substance can
> ignite or even explode if it should come in contact
> with water. Its gasses are also poisonous. There are
> safer methods of removing stains from paper. Try
> chloramine-T.
> 
> Ed
> --- "J. J. Foncannon" <bolu.bolu@xxxxxxxxxxx> 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
> > on the substance sounds numerous alarms, viz,
> > "Supports combustion.
> > Flammable solid. Can ignite in air from an open
> > flame, continuing to
> > burn as hydrogen is evolved. It reacts with water or
> > steam to produce
> > flammable hydrogen." And we're advised to use
> > "GOGGLES & SHIELD; LAB
> > COAT & APRON; VENT HOOD; PROPER GLOVES."  Even empty
> > containers are
> > suspect: "Do not pressurize.... or expose such
> > containers to heat: they
> > may explode and cause injury or death."
> >     The Library of Congress reference states the
> > material is stable in
> > alkaline solutions.
> >     Before I order any of this stuff,  I would like
> > to know what I'm
> > getting into.
> > Thanks and best wishes,
> > Jet
> >
> >
> >
> > --
> >
> > __________________________________________________
> >
> **********************************************************
> > J. J. Foncannon
> > Philadelphia, PA  19139
> >
> >  The Belgian surrealist painter Renee Magritte
> > entered a cheese store in
> > Brussels to purchase a wheel of Swiss cheese.  The
> > owner pulled a wheel
> > from the front window, but Magritte said he
> > preferred the one on the
> > back counter.
> >  "But they are identical," the owner protested.
> >  "No," Magritte insisted.  "This one's been stared
> > at."
> >
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> 
> 
> 
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>      The Bonefolder: an e-journal for the bookbinder and book artist
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             ***********************************************
     The Bonefolder: an e-journal for the bookbinder and book artist
                                    
             For all your subscription questions, go to the
                      Book_Arts-L FAQ and Archive.
                                    
                  Both at: <http://www.philobiblon.com>
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