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. ...

Apart from offering my heartfelt sympathies for having to tackle
this problem, I wanted to give you some feedback, as I just dealt
with the same media problem on an artwork, albeit on paper, which
was supposed to go abroad on loan.

The object, a Hilaire Hiler study for a mural executed with matte,
underbound paint on a completely non-absorbent piece of cardstock,
had to be treated because it exhibited not only dramatic media
losses, but areas of tenting, lifting and flaking paint. The
adhesion of the paint layer (likely opaque watercolor... think
poster paints) to the support was minimal, as was the cohesion
between the pigment particles.

I spend a good deal of time researching the materials paper
conservators tend to use when they need to consolidate (gelatin,
isinglass, JunFunori, Methocel, Ethulose, all in water, Klucel G in
Ethanol) and tested them all on a series of mock-ups. The tests
revealed that all of the above worked well (no sheen, no darkening,
no tidelines) when brush applied at a concentration of 0.5% w/v onto
a previously humidified support (I had placed the mock-up in a
humidity chamber for 3 hours).

To cut a long story short, when I thought I had it all figured out,
the REAL object didn't really behave at all like anticipated. Local
consolidation with all consolidants apart from Klucel G made paint
flakes "blow apart", and misting in a nebulizer with Isinglass (in
filtered water, concentration as above) or a JunFunori and Isinglass
mix (2:1, at 0.25% and 0.5%) didn't achieve sufficient cohesion
after several coats had been applied.

At this point, with despair looming on the horizon, my paintings
colleagues suggested Aquazol, and sent some literature my way.
Consequently, I prepared some (Aquazol 200, 5% w/v in water) and did
some more testing. On my mock-up, brush application of the 5%
solution (with a few drops of EtOH added) caused considerable
darkening in the pigment layer. Diluting it down to 2.5% and 1.25%
yielded better results (merely faint tide lines). Then I tested
whether I could actually mist the 1.25% solution in the nebulizer,
and as it seemed to work, tried it on the mock-ups--with great
results No sheen, no darkening, no tidelines *and* good adhesion.

So, in the end, the paint layer was misted with 3 coats of Aquazol
200 at 1.25%, and the edges of the losses (which still appeared
raised) were locally consolidated with a 2.5% solution. Apparently a
successful treatment.

However, now, 3 weeks later, the paint is erupting once more. Areas
which were consolidated by misting *and* local application seem
fine, but areas which were treated with the nebulizer only now sport
new tenting areas.As a result, it has been decided not to travel the
object.

A rather epic answer to your call, but it was an epic treatment.
Hopefully some of this will be helpful to you and your quest,

Nina Quabeck
Kress Conservation Fellow
Legion of Honor
Lincoln Park
100 34th Ave
San Francisco, CA 94121


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                  Conservation DistList Instance 21:54
                  Distributed: Friday, April 11, 2008
                       Message Id: cdl-21-54-002
                                  ***