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Re: Washing Watercolours



On 25 October, Roger Fry requested advise regarding the
washing/deacidification of handcolored-watercolour prints (1818).

Try contacting the Institute of Paper Conservation; Leigh Lodge,
Leigh, Worcester, WR6 5LB for a paper conservator/restorer consultant in
your area.  I do not have a phone number at hand.

Without presuming to know working habits of British conservators, the
deacification of fine art watercolours is not recommended in the United
States.  Many pigments are alkaline sensitive and may irreversibly change
color upon exposure to high alkaline (pH 10+) conditions.  A saturated
solution of calcium hydroxide in water is around pH 12+ (if memory
serves).  Of course this can be diluted to reduce the pH.  Additionally,
the binders for the pigments may be soluble in either water or alcohols.

These things are almost impossible to give advice concerning without
seeing the piece in question, which is why I suggest you find a
conservator/restorer of paper in England to consult.  The spread,
movement, or loss of the yellow color (Is it pigment? paper furnish?
binder? or?) is, in my opinion, suspicious enough to warrant further investigation into cause or other approaches
before proceeding with an alcohol/water deacidification mixture which may
have unfortunate consequences.

Dr. Vincent Daniels at the British Museum has done research and written
articles on the washing, addition of alkaline reserves, and deacification
of watercolour pigments.  As you are in the UK, it should be fairly easy
to access this information.  I do not know whether Dr. Daniels answers
public enquiries.

Good luck with your project.

Stephanie Watkins
swatkins@mail.sos.state.mo.us


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