We have a cypress ceiling installed on our porch and have a white powder
that started coming out around the knots and some spotty areas on the
ceiling. You can wipe it off but it comes back. Does anyone know how we
can clean it so it does not come back.
Is the white powder coming out of small holes? If so, it is most
likely mature powder post beetles drilling holes to lay their eggs.
Timbor is the treatment for powder post beetles. If this is the case,
any eggs already layed may not be affected by the Timbor treatment...
some eggs may be sealed away..., which means the larvae will emerge in
the spring (they will dig out of their holes) and a similar powder
will be seen as they emerge. Powder post beetles will return to the
same boards (same area), each year, to lay their eggs.
It is, as somebody mentioned, the effect of sap from the knots seeping
and interacting w/ varnish finish or simply drying.
Paint thinner will dissolve it and clean the surface, shellac that isn't
soluble by the turpenes in the sap is the effective sealer. If it isn't
finished, it won't stop until there is no more to continue to seep or it
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