Sodium bicarbonate

Does anyone have any experience using sodium bicarbonate as a
cleaning agent for the cleaning of painting surfaces and/or
varnishes? I would be grateful for any shared information about the
possible effects of sodium bicarbonate (NaHCO3, baking Soda,
natriumhydrogencarbonate) on (dried) oil colours, acrylic painting
media, and/or natural and synthetic varnishes.

There are several publications that I came across in the field of
paper conservation (cleaning, deacidification, buffering) the
cleaning of mural paintings (additive of cleaning agent AB-57), and
the use of (dry) sodium bicarbonate as an abrasive for delicate
polychrome and gilded surfaces. Due to its alkaline properties, I
would expect a leaching effect of sodium bicarbonate on oil
paintings, natural resins, and other materials that contain fatty
acids, if applied with humidity. On acrylic painting media (usually
slightly alkaline), however, I would expect no harm for the painting
structure.

Of prime interest to me are the possible risks that might derive
from an application of sodium bicarbonate on acrylic painting. In
the conservation of paper, sodium bicarbonate is applied as a
neutralizer and buffer for paper with high acid content, and also as
a fumigant. I would expect the same effect on acrylic painting
media, especially when infested with mold.

I would be happy for any comment and contribution on this matter,
and would welcome especially any corrections and criticism of the
assumptions I have made.

Ulrik Runeberg
Conservator
Museo de Arte Contemporaneo de Puerto Rico


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                  Conservation DistList Instance 19:58
                  Distributed: Thursday, June 1, 2006
                       Message Id: cdl-19-58-008
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