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I have a good amount of air-dried Walnut, Oak, Hickory, and Sassafras that I'd like to heat up to kill PPB eggs/larvae if they exist. From research on this forum and others, I've found that during a hot sunny day, stacking wood under a 6mil black plastic sheet should be able to bring the temp up to 140*, where I need to keep the wood at that temp for about 4-6 hours.

This week is that week. It is around 100F and very very sunny. It's go time.

With the amount of wood (pictured below is about 60% of it), what do I need to be careful of? Here are some questions/thoughts:
  1. With this much wood, how do I make sure the top layers of wood don't collect all the heat? I'll use stickers but how should I get some air to circulate?
  2. The boards are very different in thickness and length. How careful do I need to be about each layer consisting of the same thickness of boards? (how much risk is there of the boards cupping?)
  3. It will be hot and sunny for several days. How long is too long?
 

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You can put a small fan inside the kiln to circulate the air around. At 100 degrees, it won't take much to penetrate the wood to 140 3-4 hours per inch. If you want to make sure they all die, consider having a blow heater set at low duct to the kin and turn it on before going to bed. I would also place the stack at a slope and punch some holes at the lower end to drain any water evaporating from the wood or the top ones will get wet. You need to put a vertical board on center so the moisture travel on the wall of the plastic and gravitates down and out the holes.
 

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You will need to move the air around in the stack, while making sure you don't bring in "outside" air; the plastic will need to seal up around the whole thing. Make a cheap framework out of 2×4's to staple the plastic to, it helps a lot to have the structure. A small fan will be fine, a metal one will be better (or a heater set on "fan", no heat) because plastic ones are not made to work in such conditions. Since you are merely heating and not drying, any air movement should suffice. Just do the best you can to match up the thicker pieces with each other, it isn't that critical. Get the bottom up and off of the ground, as the Earth is really good at sucking up the heat. Without melting the plastic, you can put a couple of heat lamps under it to help out. You need to get the wood to about 135 degrees Fahrenheit, once there it's done (just like cooking a turkey). One day will do it if it will get hot enough; one of those laser heat thermometers would be helpful here. 140 is a lot of heat. Please write back as to how it works.
 

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Oh man…

Nomad - before you replied, I had already attempted the temporary kiln…and failed for day 1. What you said lines up exactly with my findings.

Try 1: I could only get to 120F, and that was only up top. The lower half was hardly warm.

Fix 1: I extended a side, added 2×250w heat lamps, and added a metal fan up top (to push heat downward).

Try 2: Still 120F! But, that was now extended to the side with the heat lamps. The opposite side was hardly warm.

Fix 2: I fixed some air gaps in the plastic that let in wind.

Try 3: 125F, but only mildly warm on the non-lamp side.

Fix 3: I built a small frame to extend the non-lamp side outward a bit. This allowes a little bit more sunlight to hit the black plastic, and more room for airflow around that side. Also during this process, I realized that this side had extra plastic, which I folded over itself to seal it during Fix 2… I believe this caused an inefficiency due to the inner flaps/folds blocking heat absorption. So, I did a roll-seam to better seal the side and reduce the number of double-layers. I also extended one of the sides outward to grab more morning sun.

Try 4: Fairly consistent 130F up top, and 128F on bottom but the sun had started to set. So, this morning I'm plugging in the heat lamps and going to see what happens.

Note: I think you were completely right about the frame. I think if I would have started with a full frame built out of 2×4's, and strategically stapled the plastic to that, I would have had a lot more sun exposure and a much better chance for good airflow within the tarp.

If this doesn't work today, I'll probably build a 4×8 extension to one end, with the bottom & sides lined with black plastic, and a sheet of plexiglass on the top to let the sun heat in to heat up the inner plastic. (with a fan in there of course)
 

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Discussion Starter · #7 ·
Alright, here are pictures for a good Thursday morning laugh.

Fix 4: I added the right wing to collect more sunlight, along with a metal fan inside that to push air slowly into the main chamber. The glass on top is from our storm door, so it has a nice rubber gasket seal around it. Stapling the plastic to 2×4s to form a nice seal was awesome.

Try 5: IT RAINED! Yesterday was ridiculously cloudy, windy, and even rainy. Amidst all of this, even closer to the evening with less direct sunlight, I was still able to get up to 125-130F. The right wing seemed to help a lot - without it, I don't think the contraption would have gotten that hot with the conditions.

Fix 5: So I reluctantly poked small drain holes in the plastic this morning, and water poured out.

So here are some pictures.

Pic 1 is about 60% of the wood that's under the big lump in 2 and 3.

Wood Wood stain Building Floor Flooring


The patchwork contraption:
Car Land vehicle Wheel Tire Vehicle


The new addition:
Plant Tarpaulin Automotive tire Grass Shade
 

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Discussion Starter · #9 ·
Dear HOA member…

- LiveEdge
Ha! Absolutely correct. Fortunately it's big enough to hide behind when cars drive by.

Fortunately I know my neighbors pretty well and they are always intrigued when I do things like this. (also we keep our place looking nice the majority of the time, so hopefully they aren't too worried). Also, fortunately in this case, no HOA.

No doubt, the next time I do this, it will be much easier. I'll build a frame and staple plastic to it.
 
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