Non-aqueous consolidants for matte, flaking paintings

Bettina Ebert <ebertbettina [at] yahoo__co__uk> writes

>I am currently treating two paintings on canvas which have a very
>matte surface appearance and exhibit extensive tenting paint, with
>associated flaking. There is almost no internal cohesion, and the
>paint layers are very brittle. Plasticising the paint with solvent
>vapours has had only minimal effect. I had to rule out aqueous
>treatments due to large amounts of water-soluble components in the
>paint layers. I have tested numerous consolidants with added matting
>agents, but have not had any success so far. ...

Lately, on fieldwork, I was confronted with a conservation problem
which is in some extent similar the one described by Bettina Ebert,
but then different again because the works of art being secco
murals.

The paintings are executed in oil colour directly on a plastered
wall. They are painted over with some matt, thick, slightly porous
and extremely brittle paint, which has lifted from the plaster
support, tearing the original oil paint up as well. The paint flakes
are large and stiff. We sent a sample for analysis, but are still
waiting for the results. The appearance of the overpaint's surface,
the characteristics showed by the material makes me think of Casein
paint, but it could easily be something else as well.

We tried to soften the flaking colour so that we could try to
encourage it flat, but completely failed with the approach. We tried
softening using different solvents and mixtures of them (water,
ethanol, acetone, white spirit, toluene, ammonia water pH 9,
ethylene glycol) applied as vapour, with a small brush in flaking
areas and/or as a compress. Afterwards we tried to encourage the
paint layer flat using a heat spatula over a thin silicone film.
Later on in the testing process we set out to try infrared light to
warm up whole areas before and during the application of solvents.
Nothing worked so far.


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                  Conservation DistList Instance 21:56
                  Distributed: Friday, April 18, 2008
                       Message Id: cdl-21-56-003
                                  ***