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Re: Paper deacidification



Peter

I forward an answer from a conservator who is not on the list.
Dagmar

Forwarded message:

It very much depends on what your are deacidifying and how you are using the
substance.  Traditionally Calcium Hydroxide is considered 'safe' only for
printed material, and not for manuscript, due it its very high pH, used in a
50/50 bath with water.  I have never considered it necessary to use this
much,  and found that by bringing the bath water up to a pH of no higher
than 8.5 is sufficient,  which gives a result in the paper of about 7.5.  If
used in smaller quantities,  therefore reducing the pH it could be used with
MSS material.  Magnesium Bicarbonate is considered the option for mss
documents, with a low pH at the time of treatment which builds up over time.
It can be used making a soda siphon,  rather than a CO2 cylinder,  but his
produces much smaller quantities.

Investigations are always being made into new products,  but the current
thought is that deacidifcation should only be undertaken if absolutely
necessary and not as standard practise.  It can do more harm than good over
time to the inks and pigments,  and should therefore be considered very
carefully.  If a document has a pH of around 5,  but has lasted three
hundred years,  is flexible and looks fine,  then a simple wash in a bath
should be sufficient to remove the soluble acids.  And then there is
washing......

Hope this helps

Hazel

Hazel Robertson
Conservator
National Archives of Scotland
Edinburgh

> -----Original Message-----
> From: Peter N Krantz [mailto:bkfndrs@OZEMAIL.COM.AU]
> Sent: 29 September 2000 05:47
> To: BOOK_ARTS-L@LISTSERV.SYR.EDU
> Subject: Paper deacidification
>
>
> Greetings to the List.
>
> From discussions which occasionally come through on the List, we note
> that many conservators use calcium carbonate as a deacidifier of paper
> materials.  Others use calcium hydroxide.  Still others use magnesium
> carbonate.
>
> We ourselves use calcium hydroxide, and we made this decision after
> reading the various researches on the subject, published some
> years ago
> in (from memory) The Paper Conservator.  At the time, we went into it
> quite closely, and weighed up the pros and cons, including
> the fact that
> we don't have bottled carbon dioxide to hand for the magnesium
> carbonate process.  (We do have the hoses and pressure gauge
> setup which
> is used with carbon dioxide, but we have not taken the next step of
> purchasing the gas itself!)
>
> Since deacidification is so important, would the learned
> members of the
> List wish to comment on one or other of these substances as
> an effective
> deacidifier?  Have there been further researches which show more
> effective new products?
>
> I hope that this subject lies within the realms of the List.
>
>
> ***********************************************
> Peter Krantz.
> Book Restorations.
> Sydney,
> Australia.
> bkfndrs@ozemail.com.au
>
> Established 1976
>
>              ***********************************************
>             BOOK_ARTS-L: The listserv for all the book arts.
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