Clay jug

Morag Wehrle <moragwehrle [at] yahoo__ca> writes

>I have an 1862 jug, made with clay mixed with dust from a brickyard.
>If it was fired, it was not extensively, as the material is quite
>soft and friable.
>
>The inside of the jug is unvarnished, but the outside is brightly
>painted.  A great deal of the paint has already flaked off, and more
>of it crumbles away with every handling.  I'm not 100% certain of
>the type of paint used, but it appears to be an acrylic of some
>sort.
>
>Can anyone recommend a consolidant or varnish that would prevent
>continuing loss of this paint layer without damaging the exposed
>areas of clay?

I would be inclined to try Acryloid (Paraloid) B72 at low relatively
low concentration in ethanol. Simple, stable, theoretically
reversible, although I doubt any consolidant is truly reversible in
extremely friable materials. One could play with solvents (acetone,
toluene,etc.), concentration, and application technique. Higher
concentrations of the stronger solvent would probably penetrate the
clay less, which may or may not be desirable. The stronger solvents
would probably dissolve the paint and the B72 may be too similar to
the acrylic to be considered truly reversible. If even the ethanol
dissolves the paint too much you may prefer to go with a PVA
emulsion (white glue), possibly diluted with water, although surface
tension effects can cause problems.

Application can be by brush or syringe, depending on whether you
decide to go for a thicker, adhesive like consistency (less
penetration of the clay, stronger bond, but more difficult to
apply), or a thinner consolidant like consistency (deeper
penetration and wicks between the cracks easily, but weaker bond).
Complete immersion is probably too extreme, and size may cause
problems with large volumes of solvent anyway.

Valerie Tomlinson
former conservator


                                  ***
                  Conservation DistList Instance 20:43
                  Distributed: Tuesday, March 6, 2007
                       Message Id: cdl-20-43-006
                                  ***