# Kiln Start Up



## ibpdew (Nov 18, 2012)

I've been lurking around your site for sometime as I'm an amateur woodworker, sawyer and now wood dryer. Thanks to Darin I purchased his plans to build our (friend and I) DH kiln. Yesterday we sawed up a couple walnut logs to use for the "test". One log was about 24" and the other was about 16" and both had quite a bit of sap wood so the slabs were pretty thick and reduced our board feet to about 300'. We stacked, sticker and started everything up around noon yesterday. This am around 8:00 I dumped our collection pail of 2 gallons and then this afternoon about 5:00 I dumped another 1 gallon. Needless to say we are pretty pleased with results so far! My friend has a sheet metal fab shop so he constructed our kiln out of 14 gauge galvanized sheets, insulated with 3/4" closed cell insulation and built (2) 5' doors that are bolted on. I forgot to mention that we did install a 500 watt quartz halogen light that between it and the dehumidifier the temperature is running right at 100 degrees. I need to read up how to post pictures for all to see plus our saw mill. I'm from eastern Iowa/western Illinois ( Quad Cities) actually. I see some of you guys are from the Illinois area too. Thx for letting me tell you about us. Don


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## ibpdew (Nov 18, 2012)

*Kiln*

I've had our kiln on line now for two weeks and I opened it up to check lumber moisture. Most of the 6/4 was down to the 15-17 percent range and one 4"x12" cant was still in the 20-25 percent range. The walnut was very wet when first loaded ( don't know why I didn't check that :huh Anyone care to speculate what the moisture content woulda been? I've kept track of how many gallons removed.


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## Tennessee Tim (Dec 15, 2010)

If you'll get a weather station that reads outdoor humidity and put that sensor in your kiln you won't have to open up to check MC until your nearly done. It will read in RH but there's charts on the net to convert to MC. I finally figured out I can set up the rain monitor under drain and convert inches to gallons. I have 2 weather stations....one at kiln and fully battery operated and ***XX # of weeks it'll store in memory and I can check and review at kiln. The other a friend gave me and it's PC computer logged. It has more bells and whistles and supposedly a great logging and read out charts BUT I don't have a computer at my storage facility to record it's memory.
Gallons of water???? WOW...I never realized how much moisture is in the wood green or wet until this kiln operation of some late 1800 logs that got wet prior to entering kiln for adjusting MC and to DEBUG for interior use. I didn't log the amount of water removed so far but wouldn't surprise me to be 80-100 gallons when done.
I have the "super kiln" version of Daren's plan.


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## ETWW (Mar 27, 2011)

Green Walnut (no drying has taken place) is about 90% MC heartwood and 73% MC sapwood. 

Walnut is also a very forgiving wood to dry with a safe drying rate of 8.2% moisture loss per day. If my calculations are right, there would be about 22 gallons of water in that 300 bf of green Walnut. At 8.2%/day that would be around 1.7 gallons of water that can safely be removed each day. If you put Oak into the kiln and dry it at the same rate, you will end up with firewood instead of usable lumber.

The average MC of most common woods and the safe drying rates are all published data. Here's a source for the MC. http://www.fs.fed.us/ccrc/topics/ur...properties and moisture relations of wood.pdf


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## Da Aardvark (Oct 11, 2012)

I'm assuming your drying this batch as a test?
Rarely do I see someone with a kiln start from totally saturated lumber when putting it in a kiln. Generally they allow the wood to air dry over time down to 25-30% before subjecting wood to kiln heat.
It reduces losses and the cracking/splitting/warping is also reduced.

My personal experience in kilning is limited and actually semi-professional. I use a blue tarp with a small space heater, and I vent out the heat/moisture. I can tell you, anytime I've dried lumber over 30%, I've had losses due to splitting. The thin lumber cuts will warp like crazy, even when stacked stickered and clamped. The thicker cuts crack and split.


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## ibpdew (Nov 18, 2012)

Da Aardvark said:


> I'm assuming your drying this batch as a test?
> Rarely do I see someone with a kiln start from totally saturated lumber when putting it in a kiln. Generally they allow the wood to air dry over time down to 25-30% before subjecting wood to kiln heat.
> It reduces losses and the cracking/splitting/warping is also reduced.
> 
> My personal experience in kilning is limited and actually semi-professional. I use a blue tarp with a small space heater, and I vent out the heat/moisture. I can tell you, anytime I've dried lumber over 30%, I've had losses due to splitting. The thin lumber cuts will warp like crazy, even when stacked stickered and clamped. The thicker cuts crack and split.


Yes this batch is a test to see how we'll it works.


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