Lime painting on plaster

Catherine Reymond <atelierarte [at] span__ch> writes

>I'm looking for literature and especially practical experience for
>consolidation of (probably) lime painting on plaster. If not lime,
>then the painting is on an aqueous basis. The plaster has sucked
>the binding material with the time and the painting is now only
>powder, just like an unfixed pastel. It's even impossible to use a
>brush on it. The only possible way of consolidation would be a
>spray, I've been thinking of pastel fixative and also
>methylcellulose but I couldn't try anything by now.

Question: Is the pigment being pushed off the surface due to
moisture evaporating from the surface and causing efflorescence? If
so, moisture issues should be understood and dealt with prior to
consolidation.

One suggestion you  may find worth looking into is the use of 'lime
water'. Slake high calcium lime, being sure to have excess water in
the bucket. The excess water should become saturated with calcium
hydroxide. Create a humid environment around your work area and use
a sprits bottle to apply the calcium hydroxide saturated liquid to
the loose pigment. The goal would be to have the calcium hydroxide
combine with the pigment and carbon dioxide to form calcium
carbonate to adhere the pigment to the plaster surface.

J. B. Blundell
PRG, Inc.


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                  Conservation DistList Instance 15:35
                 Distributed: Monday, October 29, 2001
                       Message Id: cdl-15-35-003
                                  ***