Best way to dry slabs??? Everyone seems to have a different theory

[Segerdog]

Another thing I was curious about is if anyone has ever tried using a water heater to rig up a radiant heat source for  there kiln? 
I use radiant to heat my house and was thinking a small circulation pump and some copper tubing could heat things up pretty efficiently. You could add a thermostatic control switch to keep it at whatever temp you want it. 

Haven't seen any mention of anyone trying it.... so I was just wandering 

[YellowHammer]

Steaming or using a "Steam Cycle" is a common step in wood drying.  However, if you overheat or steam some wood, especially walnut, it will cause the pigments in the wood to "run" and significantly changes the overall appearance of the wood, and reduces its desirability.  Steamed walnut looks significantly duller than unsteamed walnut.  Same with cherry.  However, if the maximum drying rate of the wood is exceeded with any heat source, the wood will crack.  The higher the temperature of the wood is heat din the initial stages, the weaker it gets, so although heating will increase the amount of moisture the wood can release, it also makes the wood more susceptible to cracking defects.  A kiln schedule generally runs at the coolest temperature possible to achieve the maximum allowable drying rate for a certain species and thickness.  

Hot water systems, usually fed by an Outdoor Wood Boiler, is a common method for heating kilns.    

[doc henderson]

we have radiant heat in our house and shop, and I would not have it any other way.  you can open a big garage door, and as soon as you close it, the room is warm again.  not so with forced air heat.  In a kiln it has been stated the radiant floor heat with warm the lower stuff first, the upper stuff is "in the shade" so to speak.  I think for a kiln using an OWB, you would want a water to air heat exchanger.   Or an old wood furnace that blows hot air in.  thoughts?  @YellowHammer @GeneWengert-WoodDoc .

[Segerdog]

I was actually thinking radiator style radiant heat.... actually running copper along the three walls so it wouldn't be as blocked. Along with a fan to move the air. 

[Ianab]

May as well put the radiator in front of the fans, so all the moving air gets warmed and then blown over the stack. 

But the Control of the drying is the trick. You have to both remove water (vent or condense with a D/H), but make sure you aren't removing the water too fast. So there is this ratio of heat / humidity / air flow that makes up a kiln schedule, and what's acceptable depends on the species (and thickness). 

Dry too fast and you risk degrade (checking / case hardening / internal collapse etc). Dry too slow and you are wasting kiln time and $S. 

The solar kilns make use of the Cheap / Fast / Good - pick any 2 principle, They are cheap, and good, but not fast. Vacuum kilns are fast and good, but not cheap.  You get the idea. You can make a cheap kiln, and get good results, but the wheels fall off when you want to make it fast.

[Segerdog]

Another question I should have asked earlier..... what's the minimum thickness the stickers should be?  
I didn't have any and Home Depot had bundles of slats pretty cheap. There only around 3/8" or so thick. I have been putting them 16" oc. There's a nice even gap all the way but wasn't sure if it should be larger. 

[Segerdog]

 

 

 

 

 

 

 
<here are some my latest.
Got into some birds eye in an elm tree. It looks amazing!!!  
Can anyone tell me what they think the other wood is?
Had a thick rough bark and big growth rings. 

[doc henderson]

elm is under rated and very beautiful.  I think what you are seeing is common in elm and Danny can give us the scoop.  some sort a epicloic somthin or other.  is corresponds to the little pointy area on the outside, and with the leaves that appear on the trunk of the tree.  @WDH 

[metalspinner]

Those slats you Mentioned are too thin, IMO. Air needs to move through that gap you are creating across those very wide boards. If you're buying from the home center, then just rip some 2x4's down. 1 1/2" thick stickers isn't too thick for those wide pieces. 

[doc henderson]

I use 3/4 inch, but we do want it to dry slow, but do not want moisture to set on the surface.  lift and edge and feel for moisture.  do not smash your fingers.   smiley_carpenter_hit_thumb

[YellowHammer]

The difference between making kiln dried slabs and kiln dried firewood is control.

[WDH]

Doc, the term is epicormic.  The buds buried in the bark are called adventitious buds.  The resulting sprouts are called epicormic branches.

[doc henderson]

sorry, in medicine we have a finding called epiploic appendigitis.  not to be confused with appendicitis.

Epiploic appendagitis - Wikipedia

Epicormic shoot - Wikipedia