White residue on ceiling


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.
------------------------------------- steven59
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steven59 wrote:

check for termites or their cousins and kill them???
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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.
Sonny
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On Sep 20, 5:29 pm, dougpotchen_at_gmail_dot snipped-for-privacy@foo.com (steven59) wrote:

I've seen what you're talking about, but I've never had to clean it off. I think it might be dried out sap interacting with the finish. How old is the ceiling?
R
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steven59 wrote:

...
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 is sealed.
--
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Somebody...? You wound me.
R
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