Finishing drying slabs by woodstove

[OntarioFarmer]

Hi everyone
I was wondering what the thoughts were about finishing drying lumber by a woodstove. I cut large maple slabs (1 1/2-3" thick x 17" x 8') with my sawmill and sticker them outside to air dry for at least a year. As nice as a kiln would be to dry lumber, it is not currently feasible. I have a woodstove in my basement that pumps out the heat in my old house. I was thinking that if I put the slabs close to the woodstove it would finish drying them out and make them more stable. I currently make signs with a CNC machine and would love to reduce any form of warping. I understand that putting green wood in house in high temperatures low humidity would wreak havoc on the boards (and potentially house from moisture), but after a year (or more) of drying would there be any harm in putting the slabs by a woodstove? Thanks!

[PA_Walnut]

Whats the moisture content of it? Time is only a vague indicator of whether it's dry enough. A lot depends on how/where its been since cut.

If you don't have a moisture meter, you can check it with an oven test. Search around here or web search and you'll find instructions.

Generally probably OK since maple can loose moisture fast and its probably at or near EMC.

Good luck!! Put up a pic of your slab(s). We are photo junkies here!  :D

[Ianab]

I'd agree with the "probably OK" verdict as well. 

If the wood has been air dried for a year, it "should" be down under ~20% moisture. Maybe don't park it right next to the stove, but in the same room where you have the warmth and low humidity. Heat speeds the drying (sometimes too much), but it's the low humidity inside a warmed room that determines what level the wood dries too. If your room is around 40% humidity, the wood will dry to 7.something%, The .something depends on the temperature, and usually doesn't matter. 

Either way, a moisture meter is you friend here. If the wood measures around 15% outside, and you bring it into a warm dry room, it will come down to ~8% , likely over a couple of months, and good to work with. 

[PA_Walnut]

Word. All of that is reasonable. Sometimes here, we get too insistent on technique and non-negotiables. For personal use, better is the enemy of good.  ;D

A point of note is sterilization also: bugs like maple (at least here anyway). Without the sterilization cycle of a kiln, that's always a potential. For items that I've used for myself, before I had kilns, I would give it a good dose of mineral spirits or denatured alcohol, in hopes that it would destroy any critters. Never had an issue. Generally speaking, most don't like dry wood anyway.

Have fun!

[GeneWengert-WoodDoc]

The slabs will dry when the humidity in a room is low...perhaps 30% RH.  This would be a normal, inside the house RH in the winter in Ontario.  Drying wood in a warm room is mentioned in Drying Hardwood Lumber, so it is possible.

It is probably best that you do not put the slabs too close to the stove, as the heat from the stove will dry one face and not the other evenly (leading to warp) unless you have a fan to stir the air around the slab.  You do have a fire danger too if you get too close.  Also, with the heat from the stove, the humidity close to the stover will be very low (5% RH) and this means that you will over-dry the wood which leads to warp and poor machining.  So, do not get too close to the stove.

When drying wood, it does release moisture, so you do want to make sure that you will be venting the moisture to the outside and will not accumulate moisture inside the house...does your stove have an outside air supply which would mean that evaporated moisture would not be exhausted from your basement?

When drying wood like maple, sometimes we get an infestation of the lyctid powderpost beetle.  To kill them and their eggs, we need to heat the wood to 133 F.  These insects like dry wood.  The holes they make at the surface are often created a year after the eggs are laid.  Because the larvae of the insects are deep in the wood, insecticides applied to the surface do not affect them.  You can read a lot about these insects here in FF in past postings.

[OntarioFarmer]

Thank you for the replies! Unfortunately I can't seem to figure out how to upload photos from my phone so I can't post my maple slabs or sawmill yet... Seems like getting a reliable moisture meter (always heard good things about the delmhorst j2000) is the way to go. I have a master craft moisture tester from Canadian Tire but have always found it to be unreliable (which is why it's probably a lot cheaper than the Delmhorst). And thanks WoodDoc for the heads up on the beetle. I've never heard of that one before so I'm definitely going to do some research on it

[PA_Walnut]

And thanks WoodDoc for the heads up on the beetle. I've never heard of that one before so I'm definitely going to do some research on it

Yep, that nasty little critter is persistent and leaves little pinholes in the wood, generally in the sapwood. They also don't seem to mind dry wood, as opposed to most others liking the green stuff, but I haven't personally had them endure very long/many cycles. @GeneWengert-WoodDoc could likely shed some light on their reproduction cycle.

[WDH]

I have had them emerge after 3 years from a customer's kitchen island top . 

[YellowHammer]

I can't tell you how many customer calls I get that start with:
 
Customer: "I bought this piece of wood from a guy, built a nice big piece of furniture and now there are little bugs crawling out of it, what should I do?"

Me:  "We'll, you didn't get it from us, we heat sterilize everything we sell."

Customer: "No I didn't, but his was cheaper and he said it had been air dried for years."

Me: "Well, air drying for years just made the bugs thirsty, :D and there are two things you can do to insure to get rid of them now that the piece of furniture is built.  Take it back to the guy you bought the wood from, show him your problem and get your money back, or .... burn it."

Point is bugs and wood are just nature doing it's thing, and I don't think I have ever sterilized a pack of live edge slabs or wood with bark on it that didn't have dead bugs on the surface when the cycle was finished.  

[OntarioFarmer]

Me: "Well, air drying for years just made the bugs thirsty
:D:D:D That's a good one! 

How long does the 133F need to last to sterilize the wood? I don't know if I'd be able to use the wood stove to sterilize the wood? ??? That might be a little too high temperature to accomplish with it. Is there another way to sterilize without a kiln? 

[muggs]

You can have it fumigated.$$$$$   Muggs

[PA_Walnut]

People love to save a nickel. :
  Have a couple of dudes locally who erode the market by selling green walnut slabs for 1/2 of market price on dried. Craigslist and Facebook buyers love the "deal" and then realize that they have to let them sit 2 years. Too bad my kiln is always filled with MY material. Sorry.

[GeneWengert-WoodDoc]

Getting the entire piece throughout up to 133 F is all it takes.  No time required.  To get this hot from a practical aspect requires the air to be around 150 F or hotter.  Any room, even a rental trailer can be used.  Be careful of fire risks and also lack of oxygen in a chamber at times with internal burners.

[tawilson]

Gene, probably dumb question but I'm wondering if you've heard of anyone using infrared heaters to heat the wood instead of heating the air?

[GeneWengert-WoodDoc]

It has been used in veneer dryers and in a few vacuum kilns. With lumberthe time required to heat the lumber will result in heating the air. Plus if the surface is hot, the EMC at the surface will be really low... not good probably.