Killing powderpost beetles in small boards

[thrytis]

I found piles of sawdust on a couple of small pieces of red oak i have. Is there an easy way to kill any remaining beetles? They are small enough to stick in the microwave or oven, though i don't really want to be running the oven for 48 hours. Can i do a higher temperature for a shorter time, and if so what is the maximum safe temperature and minimum time? The boards are about 1" thick.

Thanks!

[taandctran]

I have heard of wood catching fire if it is green and gets to hot in the center. I guess it would be much like a bail of hay. They leave it out so it will dry out for a while before they put it in the barn..

[NCPete]

I think 150* for about 2-3 hours should solve your problem

[scsmith42]

A couple of comments...

Typically a temperature of 135 degrees F is all that's required in order to sterilize lumber. The usual practice is to heat the lumber until the center of the board is 135, and then keep it there for 24 hours.

If your lumber is already dry and 4/4 or less, you should not have a problem with doing this in an oven.

If your lumber is green, DONT heat it, as you'll probably destroy it. Instead, consider chilling the board down to just above freezing and keeping it there for several days.

Scott

[thrytis]

Thanks! The boards are fairly dry, about 12%. They've been sitting in my shop for a year. I'll try 150* in the oven for a few hours.

[jeff...]

Originally Posted by thrytis

Thanks! The boards are fairly dry, about 12%. They've been sitting in my shop for a year. I'll try 150* in the oven for a few hours.

Eric 12% is a little too high, so is you temperature and your time is about 22 hours to short.

[MarkW]

I have not tried this or heard of anyone that may have but I would think that a microwave would kill anything living in your wood if its able to actually penetrate it.
I would not think that you would need a certain temperature in the wood as the bugs would die from their internal water temperature rising.

Of course, I would be careful with the timing.

[thrytis]

According to Drying Hardwood Lumber, it looks like 6 hours at 133* F are required for sterilization (after the wood reaches that temperature), "although shorter times are certainly quite effective." Red oak should be heated to a maximum of 135* F to maintain maximum strength. Maybe i'll stick it in the attic for a couple of days to drop it below 10% before sticking it in the oven, and i'll probably push the temperature a little.

I wish there was some way to test if any bugs survived (short of observing it for a couple of years). I would experiment with the microwave some.

Thanks!

[scsmith42]

Drying Hardwood Lumber is an excellent reference source!

Depending upon how quickly you need to use the boards, you could place them in the attic for a few weeks, and then sterilize them. A week or two in the attic should bring them down to 6 - 8%, AND do most of the sterilization.

Leaving it at 135F for 24 hours will provide enough time for the board to heat all the way though and then sterilize any critters.

If/when you place the boards in the attic, air flow is not really necessary (but stickering is). If there is enough wood to sticker, for air drying I prefer 1" x 1" thick stickers, and select a spot that is hot. Ideally you would place stickers every 16", and line all of the stickers up on top of one another.

The microwave concept is interesting; there are some very high dollar RF vacuum kilns used to dry large timbers for timberframe houses. The RF is used as a heat source, and the vacuum removes the moisture. In a home environment, the challenge would be to avoid overheating the wood (and thus reducing its strength or worse); I'm not sure how you could obtain a remote temperature measurement in that environment....

[thrytis]

I baked my lumber yesterday. They were about 8% when i put them in. After about five hours, i pulled out one board, drilled a hole in it, and checked the temperature with a meat thermometer. Even accounting for added heat from drilling, the core temperature was already well above the 135* target, so i ran it for another five hours and turned the oven off. There is no apparent damage to the wood or noticeable softening, and i'm confident that any bugs in there are dead. I can't recommend using the oven though, as the temperature can't be controlled enough. I had it set at slightly below 150* (the lowest temperature on my oven), but i recorded wood surface temperatures up to 170* during the process! In my case though i rescued some wood for some shop projects that otherwise would have had to be thrown out.

[JRD]

Don't know if this would work, but the question started me thinking.

If the pieces are small enough, what about a DNA bath? A strong alcohol dunk usually kills just about anything, so just like we turners do with green wood, soak it for a day, then since it's already dry, let the alcohol dry out for a few days, and I'd think the oak would be ready for use again.

Maybe, I just don't know!

Jim

[thrytis]

Originally Posted by JRD

If the pieces are small enough, what about a DNA bath? A strong alcohol dunk usually kills just about anything, so just like we turners do with green wood, soak it for a day, then since it's already dry, let the alcohol dry out for a few days, and I'd think the oak would be ready for use again.

I've never heard of this before, but then again i don't turn. Do you just submerge wood in denatured alcohol for 24 hours? Is that a proven effective method of sterilization? Is there no expansion of the wood because it is alcohol?

Thanks.

[JRD]

Don't know with certainty that this is an alternative treatment, only that the question started me thinking.

Since DNA is 90 percent alcohol, it dries very quickly and has the added advantage of absorbing water. Alcohol kills almost anything submerged in it and that it comes into contact with, so the soaking method seemed to make sense.

I did use it one time to kill some wasp larva that had tunneled into a piece of Pecan I wanted to use. After a day in the alcohol, and a day drying, only dead larva, and I was back to turning.

Maybe there are some other ideas on this.

Jim

[huckster]

When i harvested a tree and milled a red oak I used a product called Bora Care (Bora something) its a pesticide. I don't know how long it stays active but it killed the bugs. I think once the wood dries and gets below a certain MC and is "cured" bugs don't go for is so much. That was a lot of board feet and wouldn't fit in the microwave

2-cents

~Huck

[dave "dhi"]

eric,
i suggest some oven cleaner also, if the oven isnt self cleaning!!!

i see a ton of first on this site! "honey ,can u go check the walnut in the oven".