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Fixing Wood Infestation4/6
I've been asked to fix an old table (circa 1500s) that has been infested with some sort of beetles— possibly anobiids, as the hole size is ~1/8". Few if any holes come through to the surface, at least visibly, though I haven't had time to inspect it thoroughly.
The table weakened to the point that a ~2-1/2" square leg snapped. The inside looks about as solid as a common household sponge. The holes are filled with a fine powdery frass
The owner has stored the table indoors for several years in an unheated, dry space. Winters here usually get down to zero, though the transitions are gradual. She assures me the bugs are dead, and I see no evidence to the contrary.
My thought is to stabilize the wood by using a penetrating epoxy, then drill and dowel the break with a long dowel bedded in epoxy.
I've been searching the web for pointers on the best fix, to no avail. Does anyone have experience they can share?
1) on killing the beasts— is the freezing I describe sufficient?
2) on stabilizing the wood with penetrant— has anyone tried this? Any particular brands that do or don't work?
Thanks in advance for your help.
I once found some frass on the basement steps of our first house. The termite guy came out and drilled some holes and did an injection. I was shocked when I saw all the wet paint from pesticide coming out of so many places! It was like the paint was holding it all together! I bet this table is the same way. Freezing causes some insects to go dormant. There is a life cycle to other bugs and the eggs hatch in the spring for the next cycle. High heat is the only proven method. If a 2 1/2 leg snapped, that table needs to go to the dump. I sure wouldn't want to bring it into my shop or want to give a warranty on the work!
The table is probably worth several times more than I gross in a year. It is getting fixed one way or another, and I want to be part of saving history this significant.
I've read about freezing on several websites and would like to hear from someone with knowledge or experience.
What I haven't seen in a couple hours of searching is successful treatments for the structural instability, or experience based solutions to strengthening the wood. My intuition tells me that a penetrating epoxy may be just the ticket, but I'd like to know it before I blow it.
The first step is to kill the beetles and their larva and maybe eggs. This does sound like the lyctid powderpost beetle, but the holes are twice too large, so it must be a different beetle. The lyctid is the only one .that gets into very dry hardwoods. You can kill the insects, larva and eggs with heat...over 133 F throughout the wood. So air temperature is around 150 F. This will dry the wood out, so make sure you have wet towels or other moisture source to keep the humidity up. You can also fumigate, but that is expensive.
I cannot comment about restoring the strength, as getting a thick material throughout the wood seems impossible and then epoxy would seem to risk destroying the antique value. A good museum curator can advise you.
A penetrating epoxy will just provide a hard skin, certainly not going to the depth for full penetration of the leg. So not structural at all. It would take submersion in a vacuum chamber to get full penetration, and that would also require it to be raw wood. Knife scales (handles) are the prime example of full resin penetration of wood. Those are done under a hard vacuum, then baked to set the resin. If the table is worth that much, I suggest you get it x-rayed at a museum furniture restoration company to really evaluate the extent of the damage, if they allow the table in their shop. If the leg is at the stage of "household sponge" that you said, the value will be far less than you suggest.
Rich c— are you saying that an epoxy advertised to penetrate rotted wood will be unable to flow through holes as I describe? I'm surprised— even thick epoxies seem to thread their way through the tiniest hole, if their set time is slow enough.
Have you used penetrating epoxies in this type of wood?
Are you just talking about just treating that single section of the broken leg? I assumed the leg was infested all the way through, top to bottom. I also assume there is damage through the rest of the table. Hard to imagine they just attacked that one leg. You won't get it to flow all the way through 2 1/2" of wood that isn't broken open. No problem flowing into holes, much tougher to get into wood at the cellular level. I've used one part wood hardener, not thin epoxy.
You cannot freeze insects of this sort to death until maybe -30. The insect eggs might still be present.
Epoxy does not work well if it is too small of a quantity in one spot. In needs a thick glue line, etc. This is because it must generate heat in order to cure. A thin layer, or some in a 1/8" hole, is likely not to generate enough heat. It is surprising how many people use way too much pressure with epoxy and then have a weak joint. Further, epoxy is thick, so it will take lots of pressure to force it into the length of a hole. Tough to imagine how pressure can be used to get epoxy only in the holes and not on the wood surface. Not all tunnels in the wood are connected to a hole on the surface. How will one get access to the holes in pieces that do not have the holes coming to the surface? Further, as stated, many of the holes have dust in them that will stop liquids from penetrating. (technical term for insect dust is frass)