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Thread: How hard would it be to build a kiln just to kill powder post beetles?

  1. #1
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    How hard would it be to build a kiln just to kill powder post beetles?

    I am tearing down my old barn and building a new shop. I have seen evidence of PPB on some of the lumber I had stored in the old barn. Would like to stop any transferring to the new barn. Could I realistically make a 4ft by 4ft by 12ft kiln to put lumber in just to heat enough to kill the beetles?

    What is a cheap heater that can get it hot enough? Could I just build it out of styrofoam? It would only be temporary. Run a few batches through and take it down.

  2. #2
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    Quote Originally Posted by cody michael View Post
    I am tearing down my old barn and building a new shop. I have seen evidence of PPB on some of the lumber I had stored in the old barn. Would like to stop any transferring to the new barn. Could I realistically make a 4ft by 4ft by 12ft kiln to put lumber in just to heat enough to kill the beetles?

    What is a cheap heater that can get it hot enough? Could I just build it out of styrofoam? It would only be temporary. Run a few batches through and take it down.
    Can you contract with a local kiln to treat the lumber?

    Some people have reported making solar heaters from an insulated chamber with glass or several layers of clear plastic and leave in full sun in the summer. You can read on the net but some sources say heating until the core of the wood reaches 135-deg F and holding for 6 hours will kill any in the wood. Others say that temp needs to be held longer.

    Also, I would be cautious about any advice to spray the wood with this or that insecticide. I don't see how it could penetrate to the center of the lumber. PPBs are notorious for emerging from the wood several years after such treatment. I got some walnut 2x2s from a guy who said he sprayed them well with something powerful. I had some on the shelf at my last shop - one day I heard a faint "scritch, scritch, scritch" sound and actually watched one eat it's way out of the end grain.

    JKJ

  3. #3
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    I contemplated doing this, I don't think it would be hard. Insulation is your friend, I'd build the box out of 2" thick pink foam, perhaps doubled up to 4". For one time use it could just be taped together. A "dairy heater" or a bunch of 100 watt incandescent bulbs in porcelain bases should provide enough heat, though it will take a long time to heat up. A small fan will help the pile to equilibrate. I bought this temperature controller which has turned out to be useful for a whole variety of things.

    I'd follow the USDA recommendation, which is something like 140 deg for 6 hours-- but keep in mind that's for the middle of a board in the middle of the pile. It may take a very long time to heat the whole pile to that temperature.

    Heat is certainly the safest and most effective treatment where it is possible. I have had good success (knock wood) with Boracare where heating was not an option-- my barn, now shop, had an awesome infestation of PPB. The exterminator I called said he'd never seen anything like the hatch I had, many. many thousands of them emerging at once right after I finished the new hardwood floor-- perhaps an effect of the solvent on them? I sprayed the entire interior with Boracare using a garden sprayer. Eight years on there has been no sign of new bug activity and I watch pretty closely. The borate blocks new egg laying and also, I believe, emergence of the adults by leaving a surface layer that is toxic to the bugs for many decades (borate is very safe for humans and other mammals). They may well still be alive inside, but the life cycle is broken. Probably not useful for wood that is going to be further processed.

  4. #4
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    boric acid is the white powder sold in mustard squirt bottles to kill roaches. It is also the active ingredient in Terro ant bait. Some thing about boric acid cuts their exoskeleton or something. Good thing is it takes a few days so they go home and others groom it off and onto adults, queen, the babies and eggs. No smell no taste
    Bill D.

  5. #5
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    I posted about it here before. I built a dehumidification kiln in my wood shed using 2" foam board over 3-1/2" of fiberglass with a plastic vapor barrier.



    The kiln is 12' long x 4' x 4' and will hold about 500 bf. There is a blower to circulate air through the stickered lumber, a 30 or 40 pt household dehumidifier to remove moisture, and a 1500 W oil filled radiator heater. I use the kiln to dry AD lumber down to 6 - 8%, year round. It costs less than $50/month to run even in the dead of Winter in WNY. I follow EBAC's kiln drying schedules except I do not heat above 110F while using the dehumidifier because it has a thermal overload around 125F. After I get to 8% MC, if I'm concerned about bugs I shut off the dehumidifier and just use the heater to heat up to 140F and hold there for 24 hours. The key is the insulation. It doesn't take much power, less than 1500 W, to get to 140F if you have a good insulation package. I only have the 2" foam on the door but it still has no trouble getting to 140F.

    Many oil filled radiators have thermal cutout switches. To use one you either need to find an older one that does not have that feature or bypass the circuit for it on a newer one. Also, digital units will not survive, so you want a dehumidifier and heater with mechanical controls. You could use other types of heaters but an oil filled radiator is safe and cheap so that's what I chose.

    I use low cost electronic controllers to run the dehumidifier and radiator.



    It cost less than $400 to build (I already had the dehumidifier, heater, and blower. You could easily build something like this, or even a more temporary unit, for not much money that will safely do what you want.

    John

  6. #6
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    Thanks guys, would a infrared eden pure type heater work? Or like the little bathroom electric fan heaters?

    My thinking was along the lines you posted above. Make a Styrofoam box and put heater inside.

    I appreciate that temp controller link that will be helpful.

  7. #7
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    Quote Originally Posted by cody michael View Post
    Thanks guys, would a infrared eden pure type heater work? Or like the little bathroom electric fan heaters?

    My thinking was along the lines you posted above. Make a Styrofoam box and put heater inside.

    I appreciate that temp controller link that will be helpful.

    You don't want an infrared heater or anything else that glows. You want a radiator type heater which doesn't get hot enough to combust wood even if pressed against it. I use one like this one: https://www.amazon.com/PELONIS-PHO15...n%2C175&sr=8-6

    Mine is older and has no high temp. limit switch. Most new ones do; if so, you likely will have to bypass it to get to 140F.

    How large does the heater need to be? It depends upon how large and well insulated and sealed the box is and the ambient outside temperature. For the box I built with average R20 insulation 1000 W is more than enough to heat it to 140F even at 20F outside.

    Here's a link to the temp. controller I use, which can handle 1800 W: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    John

  8. #8
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    Christian Beeksvoort wrote an article in FWW in November 2009 about a home based sterilization chamber. If you PM me your email address I’ll send you a copy.

  9. #9
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    Quote Originally Posted by Scott T Smith View Post
    Christian Beeksvoort wrote an article in FWW in November 2009 about a home based sterilization chamber. If you PM me your email address I’ll send you a copy.
    Do you know the issue # Scott. There is an October and a December issue for 2009 but I couldn't find it in either. Thanks.

    John

  10. #10
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    I think that it is issue #202, Nov. 2008
    https://www.finewoodworking.com/2008...harden-the-sap

  11. #11
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    I have been keeping my mouth shut for a couple weeks in case I could learn something. I know from other threads Scott T Smith has his hat on straight and so on, as do, on review, all the other posters in this thread. I would be interested to see the plans for the sterilazation kiln myself, but otherwise it looks like the best options are to 1) build a full on drying kiln and look for local green wood after existing beetles are killed, 2)toss the existing lumber in the firepit to grill hotdogs or 3) look at the sterilization kiln pretty hard.

    At the end of the day it will come down to how much space you have, how much money and time you have, and how much affected lumber you are looking at. If you got walnut, forget about cooking on it.

    I did follow Brice's link. Holding a 4x4x12 volume at 170dF is going to take some serious BTUs. I would go smaller and batch process with a smaller heater, maybe 2x2x12 and four batches. I seem to be less than a week away from firing up my woodstove up here. In Michigan could you run a camp stove in the barn with a single wall flue under the sterilization kiln (longways) to get some cheap BTUs into the kiln envelope? Safely?

    Sucks to throw away a cord and a half of lumber for sure, but it also looks expensive to save. If it was from the oak tree that lived in front of my grandma's house I would probably spend the money and hope the beetle damage wasn't too bad once I started building stuff. If it was Joe Birch from the local saw mill I would wear out a pencil point or three looking at energy costs, but probably cut it into 16" lengths for the wood stove - because I don't have room for a permanent kiln.

    Best wishes and good luck.

  12. #12
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    Quote Originally Posted by Brice Rogers View Post
    I think that it is issue #202, Nov. 2008
    https://www.finewoodworking.com/2008...harden-the-sap
    Thanks Brice; that's the correct issue. I have to say, it's a rather crude device but probably serves the intended purpose of setting pitch on a few boards.

    John

  13. #13
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    Scott, if you reread my first post you'll see that you can build a 4 x 4 x 12 ft insulated chamber and heat it to 140F with just 1000 W of heat. You don't need to go to 170F. According to the FPL a sustained internal wood temperature of 135F for 3 hours will kill any and all bugs. I dry/sterilize 400bf of AD lumber in my kiln in the dead of Winter for less than $50. In the Summer it's less than $20.

    You can adjust the size of the kiln to whatever best meets your needs. If the walls, ceiling, and floor are insulated to a minimum of R23 you will need less than 5 W of heat per square foot of exterior kiln area to heat any amount of wood that fits inside it to 140F when the outside temperature is 0F.

    It's not hard or expensive to do.

    John

  14. #14
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    Let me suggest an experiment;

    Start with a chunk of wood in an oven. 4 x 4 x 12 oak with a meat thermometer into the center. Set the oven to 140 and see how long it takes to get the inside to 135.

  15. #15
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    Quote Originally Posted by Tom Bender View Post
    Let me suggest an experiment;

    Start with a chunk of wood in an oven. 4 x 4 x 12 oak with a meat thermometer into the center. Set the oven to 140 and see how long it takes to get the inside to 135.
    Good idea. The time required varies depending upon the MC% of the wood. The higher the MC, the longer it takes to get to temp. Similar to baking a cake.

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