Binder for cellulose powder

Lori Arnold <woodbldg [at] aol__com> writest

>I am working on a large architectural wood conservation project that
>requires aesthetic repair on termite-damaged polychromed ceiling
>beams in an 18th century chapel. The termite activity is not active
>in these locations, but there is always the possibility of it
>returning. I do not want to use a non-reversible repair, such as
>epoxy. ...

I have had some good success using cellulose pulp/powder in 1% CMC
as a paste filler for worm eaten wood.  The wood has to be
consolidated first (I first saturate it with 5% Butvar in ethanol,
so this may not be compatible with your painted surfaces) to prevent
the damaged wood from being affected by the water, and to strengthen
the wood a little.  Then the cellulose paste can be injected into
holes, and when dry, is very strong, light and reversible to a point
(theoretically it reverses in water but getting into crevices to
reverse it would be difficult).  It shrinks down while drying,
requiring an additional layer or two.  The resulting fill is not
super smooth, but can be sanded, smoothed with water and painted. Or
a water-based spackle can be used on top for a smoother surface.

If the gaps are very large and deep, you would have to build it up
in layers, as it would slump, and the water takes a while to
evaporate. Ethanol-soluble cellulose ethers can be used to make a
paste too, but it does not create a strong result (stays soft and
spongy when dry).

You could add borates and I don't think it would adversely affect
it, but I have not tried it.  Pigments can be added, but there is a
marked color change in drying (it gets lighter) and getting an
intense color is tricky.

My attempts to used water-dispersed synthetic resins instead of CMC
did not have such satisfying results.

Hope all this might be of some use to you,

Linda S. Roundhill
Art and Antiquities Conservation
18121 157th Ave NE
Woodinville, WA 98072
425-481-0720


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                  Conservation DistList Instance 19:1
                 Distributed: Wednesday, June 15, 2005
                        Message Id: cdl-19-1-004
                                  ***