Hey y’all. Newbie to the forum and drying lumber. I have a 7″ x 10″ x 100″ long piece of black walnut that I plan to kiln dry and cut to 72″ long when dry. MC is ~ 72%. A co-worker let me borrow his homemade kiln. It is a large 2×4 frame with foam insulation nailed to the out side. There is a large opening that I have my small home de-humidifier connected to to pull the moisture from the kiln. The “exhaust” side of the DH is connected to a dryer vent aluminum flex hose pushing warm air back into the box (for heat). Box temp is ~95 degrees. See pics for my Red-Green getup. Any tips and advice as this piece of lumber begins it’s drying journey would be appreciated.
Also, I’m thinking of finishing the mantel with Tung Oil after it’s been planed and milled (for hanging brackets). Considering using Real Milk Paint Co. Half and Half tung oil & citrus solvent. Any thoughts and advice on the finish would also be taken into consideration.
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Rather than going just by a moisture meter, I would weigh the walnut periodically, and record them. When the weight stops going down, your kiln has probably done as much as it can.
Good idea but it'll have to wait til the MC meter stops goin' south. This thing weighed 290lbs going into the kiln.
You might want to cut it to 80" or so to save time and get the bulk of what you'll be using closer to the "outside" of the stock. The center will be the last part to lose moisture. Take some off of both ends to equalize them.
Another good idea but should I worry about the ends checking too much? Maybe I'd leave it heavy by 6"/end to be safe? This thing had a MC of 72% going into the kiln. That concern and also it's a heavy pig to lift and move around. I rigged a chainfall to lower it in. I can use it to pull it out and set it on some horses and go to work with my circular saw to shorten it. Then I'd get another weight, before and after I cut it down.
I agree with cutting it down now. It will help the parts you want dry more evenly. You can coat the ends with Anchorseal or something like it to help prevent checking. I can't tell how the airflow is in our kiln. If it's not even all the way around the wood, you should consider periodically rotating the wood. The goal is to get it to dry as evenly as possible to guard against warping, twisting and bowing.
I love The Real Milk Paint Company Tung oil and citrus solvent finish. Although I recommend buying them separately and mixing on your own. 50/50 is a good start point for the first 3 or 4 coats, but later coats you might want to increase the amount of tung oil. As a bonus, it will also make your shop smell like oranges.
As a thought, you may have made your set-up more complex than it needs to be. Can you set the entire dehumidifier in the kiln? The only thing you need to vent is the extracted water. A drain hose should be sufficient. If the dehumidifier isn't circulating enough air, a small fan may help.
Is there any difference between Classic Anchorseal and Anchorseal 2? I can get the classic version by the weekend.
This kiln is borrowed from a co-worker so I simply followed his instructions but I like the idea of putting the DH inside the kiln as long as it doesn't overheat or require fresh air for regulation?
Thanks for the tip on the Tung Oil.
No suggestions, but a question: Do you have a moisture meter with prongs long enough to get deep into the wood? I couldn’t accurately use my pinless Orion 930 on a piece that thick, it’s “deep” setting is 3/4”, which works fine for up to 8/4 or so, but thicker than that is educated guessing.
Good point. I only have the electronic 1 in the image that has a surface rest sensor. The only other MC meter I have at my disposal is a handheld 1. I'm going with what another poster above suggested about weighing the piece until I don't see any negligible change (after my MC stops producing lower readings).
Good plan. Not unnecessarily cutting to exact length is also a good plan, but since you'll be eventually trimming 28" off the length when it's dry you could cut half that length off one end now (I know you said that would involve removing the wood from the kiln), keep the cutoff in the kiln and remove that lighter piece periodically to weigh it so you don't have to move the big piece to weigh. Unless you have a scale that could just stay under the big piece till it's dry, if you could read it while under the wood.
Would there be any advantage to drill 2 small holes into the rear/wall side of the mantle deep enough to get 2 long probes in for a handheld MC meter or would the holes allow the moisture to escape not giving a true indication of the moisture content. Maybe I could seal the holes temporarily during the continued drying process? Found this 1 on Amazon:
https://www.amazon.com/Display-Digital-Adjustable-Moisture-Tester/dp/B07P11F536
I've never seen a meter with probes that long... the specs say it is for tobacco and cotton. I don't think it will make much of a diff, but for fifty bucks what the hell? if you don't mind drilling the log you could put a whole bunch of large deep holes in the back to speed the drying process and lose some weight.
I'm surprised no one has mentioned what I consider the elephant in the room - the fact that drying a 7x10 by very long piece will take a long, long time, kiln or no kiln. If you air dried it, count on many years. Matt Cremona has a video where he talks about drying thick slabs in a vacuum kiln. He achieves less than 10% MC in a few weeks, but says (if my memory serves me) that a regular kiln would take way too long to even try. If I'm missing something here, I welcome good information from people with first-hand experience.
You read my mind, what is the recipie to dry 7 " thick Lumber. 1 inch will take weeks, this will take months assuming the process is controled. Under those circumstances, keep the ends to full length, the cheking will be going far in the ends.
No mention of a time constraint so it is what it is.
You may be able to solve one problem with the other. To test the moisture, cut 4 or 5 inches off the end and test the end. You can then get a read on how the center is drying. Just make sure you reseal the end each time to prevent checking. (There is no significant difference between Anchorseal and Anchorseal II.) You could do that 5 or 6 times and still have enough for the mantle. The cut offs might even make a nice bowl blank to sit on the mantle when it's finished.
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I have another point to make. MikeDilly says this will be a mantel. Just how dry does it need to be? Do we really care if the center part has high MC? Do we care if it moves a little? A big beast of a mantel like this one looks fine with character. If it was mine, my goal would be for it to remain relatively flat and the finish stable over time. Also I would probably accept that I would be touching it up with a hand plane and finish in 5 years if problems with either occurred.
I was leaning this way too.
Exactly! We're not going to make "fine furniture" with this. I can live with it moving a little hanging on the wall but the movement will be somewhat constricted due to the 60" custom hanger hardware I plan to use. I just don't want it to look like an over ripened banana hanging on the wall :-) Keeping this in mind, wondering what would be an acceptable MC? Perhaps I can also gauge any movement & end checking after a month in the kiln?
I was about to warn about sealing all that moisture inside with a finish, and I’ve read about white spots appearing in a tung oil finish when the wood wasn’t completely dry, but I’m thinking that a chunk of wood that big will have lots of checking as it dries, so there may be plenty of places for moisture to escape. And checking adds character. Here’s my mantle, salvaged from our 200 year old barn (my woodworking shop is in our 1840 barn).
I would not be concerned if it is 12% MC since its a standalone piece and further mouvement will be minimal . Drilling large holes from the back would certainly help drying both in the kiln and once installed, coring to an even 2 inches thickness from the back even better.
Honestly I think you are going to run yourself ragged trying to dry that thing out and the instrument you need to properly test it is about a grand. My first suggestion is to try to find someone in the area that has some experience and the right equipment and it should run you less than 200 and you will have the mantle a heck of a lot faster.
My second suggestion is to dry it out the best you can, accept that there may be some checking and cracks, and install it using a system like Sheppard brackets (www.sheppardbrackets.com) to install it and allow for serious wood movement.
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