# Kilning and Sterilizing...A MUCH confused process(s)



## Tennessee Tim (Dec 15, 2010)

I'm only going to hit the high points, these DEFINITELY ARE NOT all the points or facts due to complexity of differ woods and processes.

There's many factors in drying, kilning and sterilizing. Most confuse kilning and sterilizing as one and the same and they AREN'T!!!!

Kilning is just a way/format of drying the wood in a speedier controlled process that also allows one to bring to a lower MC than ADing. 

Sterilizing is a process of killing bugs and other pests. This can be by chemical, fumigation or as most known HEAT!!! Sterilizing is best done AFTER the MC is brought down to the desired level. There is a newer style where I hear they're extreme heating first BUT I have my reserves about due to MC being TOO high in the beginning which causes stress and checking.

The reason it's thought of as the same is because usually the both are done in the same building/setting.

From all my readings adding too much heat or just dropping MC TOO fast causes major issues when the wood is above 20-25% MC. This causes stress, checking and other issues. That's why green wood has differ MC loss schedules to help prevent the above issues. The readings I've done, most state once below the 20-25% MC it's hard to mess up the lumber.

Drying lumber myself is done via DH with a little heat...90-100 degree is ideal BUT I don't get concerned IF I'm in the 70's....the DH is pulling out the moisture....I set mine @ 30% RH(approx 6% MC depending on temp) and let it run until it quits pulling out moisture for a week or 2, NO need to rush, LET it balance itself out internally.....THEN I sterilize.

A small fan, DH, and a 100 watt lightbulb under a sealed area is ALL
you need to dry the lumber, the light is only to get heat started, after that the DH will produce it's own heat from running......sterilize with the big heat AFTER it's MC correct.

I'm sure there is points I've overlooked and missed BUT this is a base to start from and different views. It's like driving a car, SPEED KILLS and that has many factors built in to outcome.


----------



## aardvark (Sep 29, 2011)

And yet, I still drive over the speed limit.

It might be said certain species of wood react differently, but I'm no expert on that. I just push the limits and try to get it done.


----------



## laxin213 (Jan 25, 2013)

DH = dehumidifier? Thanks for the post. Learning what I can on the process, maybe one day I'll build my own solar kiln. The rule is to not mix species of wood in the kiln at the same time, correct? Each species has its own "drying cycle"?

I have had load of hard maple this past summer that were dropped near my house. I took some logs to mill and then a big commercial kiln and they sat in their yard for months (August- dec). Stickered, but nobody wanted to deal with them their since they had all these huge orders of thousands of Bf and here's my load of 6, 7, and 8 ' maple like 600 bf. The sales guy on the phone made it sound like they could do it asap, but the lot guys could give a crap less. Many phone calls produced Nothing in follow up. I ended up picking them up, I just drove into their lot, loaded up my wood and left. Nobody stopped Me and the guy I spoke to there never called and said a word. 

I took the wood about an hour in the opposite direction to a guy that dried them in his kiln, a much smaller setup, in about 8 weeks. Very nice, fair, and charged me less than they quoted me. I found kiln driers in the State DEC website, they encourage kilns for their sterilization of the invasive bugs.


----------



## aardvark (Sep 29, 2011)

I don't know why differing species can't be died together. There is (to my knowledge) no reason why the cycle can't be interrupted to pull certain dried pieces out and continue the cycle on the rest.

The reason you type of and the costs involved are why I set up my own "Cheap Kiln"!
Theres a posting on my setup. Cost is under $100.oo with a moisture meter included in the price.
Good for small loads.


----------



## Tennessee Tim (Dec 15, 2010)

Aard said:


> And yet, I still drive over the speed limit.
> 
> It might be said certain species of wood react differently, but I'm no expert on that. I just push the limits and try to get it done.


 LOL on the speeding , remember I've rode with you....definitely NO brakes on my side!!! I'm trying to get good info out so we all don't "speed" through the process without knowing what can/can't happen to their wood. 



laxin213 said:


> DH = dehumidifier? YES Thanks for the post. Learning what I can on the process, maybe one day I'll build my own solar kiln. The rule is to not mix species of wood in the kiln at the same time, correct? Not necessarily Each species has its own "drying cycle"? YES BUT that also depends on the starting MC. With the home DH it probably couldn't pull a load down too fast (I'm guessing)
> 
> I have had load of hard maple this past summer that were dropped near my house. I took some logs to mill and then a big commercial kiln and they sat in their yard for months (August- dec). Stickered, but nobody wanted to deal with them their since they had all these huge orders of thousands of Bf and here's my load of 6, 7, and 8 ' maple like 600 bf. The sales guy on the phone made it sound like they could do it asap, but the lot guys could give a crap less. Many phone calls produced Nothing in follow up. I ended up picking them up, I just drove into their lot, loaded up my wood and left. Nobody stopped Me and the guy I spoke to there never called and said a word.
> 
> ...


----------



## aardvark (Sep 29, 2011)

Hey, I kept it under 90.
Ha!

From your standpoint I agree with everything your posting, ESPECIALLY THE BUG KILL !!!!. If you sold bug infested wood, that might be a heck of a liability issue. If I sold finished furniture and all of the sudden there was sawdust on the floor,,, Not Good Either !

I do push the limits when drying for myself as you (Tim) well know. That oak pyramid I put in the kiln at 50% m.c., but I was counting on the cracking and a little warping happened as well. I incorporated it into the design and filled the voids with epoxy. I didn't compromise on the bug kill, however.
When I kiln wood that is higher than 25% I can count on a appreciable loss of product due to cracking and twisting. If you can live with those losses it's up to you, but I'm the exception to the rule here. Most would not do as I do.


----------



## Tennessee Tim (Dec 15, 2010)

Aard said:


> Hey, I kept it under 90.
> Ha!
> 
> From your standpoint I agree with everything your posting, ESPECIALLY THE BUG KILL !!!!. If you sold bug infested wood, that might be a heck of a liability issue. If I sold finished furniture and all of the sudden there was sawdust on the floor,,, Not Good Either !
> ...


And THANKS for keeping under 90.....I don't know if the floorboard could handle anymore...LOL!!!! I did enjoy the trip...

**JUST FOR the RECORD, Aard was much safer than we sound here...I drive more defensively and he drives more offensively. I have raced and LOVE IT ...BUT... on the highways and byways I'm reserved due to being a extractation tech and I've worked ALOT of unnecessary crashes and deaths.

When I kiln wood that is higher than 25% I can count on a appreciable loss of product due to cracking and twisting. If you can live with those losses it's up to you, but I'm the exception to the rule here. Most would not do as I do.[/QUOTE]

This is the part I want others to understand, as you and I have discussed this prior to these posts. 

In large junks/logs/slabs, there is loss at both paces in drying but as long as a person knows this up front than it's their call. Also in large chunks as the pyramid, deep EMC is almost impossible in a short time frame except maybe by vacuum kilning.

Also drying as for lumber and slabs needs the EQUILIBRIUM balance with the MC for lumber to stay stable and speed doesn't always get that.


----------



## bmarshall9686 (Jan 17, 2016)

I suggest using a hair dryer about 6 inches away, you can dry 1 bf in about 6 weeks


----------



## aardvark (Sep 29, 2011)

Hey, TIM. That floorboard wasn't too rusty. It could have handled 120 and a heavier foot press.
I take offensively to that!
Ha!

marshall
Maybe pen blanks?

When Tim cut up a green (wet) oak pyramid for me, 4 sided w/ bottom and all sides 20" long, the m.c. was around 50%.
I roughed it out further than his chainsaw cuts and immediately got it into a kiln. First I weighed it and it came in at 83 lbs.
After 2 weeks of constant hard kilning the weight drops stopped and it was at 52 lbs . Lotta water weight was lost
. I kept kilning it and the weight didn't drop any more. Essentially it was as dry as it could go. Outside measured less than 6%, but the inside was uncheckable. It had cracked and split in about 3 locations and the side twisted.

You see the standard rules were broken. I don't advocate anyone does this. Tim's methods are correct and as he says, "If a person knows up front, it's their call".

When you are kilning for others, the rules apply.
Tim didn't kiln it,,, I did. He had reservations to what I was doing.


----------



## bmarshall9686 (Jan 17, 2016)

Would this same rule apply to a solar kiln?


----------



## Tennessee Tim (Dec 15, 2010)

bmarshall9686 said:


> Would this same rule apply to a solar kiln?


Yes Solar kilns have regs also.....believe it or not ADing has rules and regs. even though it's a slower process. Some woods can tolerate a fast MC removal while others need a slow. Solar kilns have vents to open and shut to regulate the loss rates and to help control the temps. There's a group out of Wisconson or Minnesota that have GREAT info on solar kilning. Their layout is one I've considered very much...it has a good heat trap source with a better regulating system where the wood isn't directly in the sun/heat chamber....very well thought out!!!

ADing....YES I take measures to protect my wood from the elements and direct sunlight, BUT I also have to make sure there's enough fresh air exchange to prevent molds.

One of the best in our lower production world that was VERY helpful is DAREN....he had a way of explaining in plain chat the most of us could understand.

I've read many theories on drying....YES they're theories/ideas...and I took valuable info from all of them and comprised what I seen as a natural event and what would be TOO forceful. Dr GENE on woodweb.com has been very helpful also....he understands the high production end of drying....this/these idea(s) require a lot of gauges and gadgets to stay in precision controlled correct push the limits without destroying. I wasn't interested in going that far BUT I/you still need to know the basics and fundamentals of what is good and bad whether large or small scale of drying.

The main thing is KNOW the fundamentals and decide WHAT you're willing to RISK or NOT.


----------



## aardvark (Sep 29, 2011)

The problem I see with solar kilns is the temperatures are inconsistent and dependent on the sunshine, or lack thereof. 
At night, there is nothing. So the wood temp varies hour to hour. If you have a massive stack, the stack will retain (most of it's ) heat overnight, but smaller stacks can't do that as easily. And then...what happens the next morning if you have a number of cloudy days?

I try to keep my stacks at 90 degrees 24/7 and a bug kill cycle towards the end and back to 90 again for a last day and slowly drop off back to room temp for a number of hours before removing the wood at the very end.
I simply can't see how that would be possible with a solar kin.

Maybe I'm uninformed here and beg to be corrected if I'm wrong. 

Upside is there is no cost for fuel/electricity to keep heaters going.


----------



## bmarshall9686 (Jan 17, 2016)

Aard said:


> The problem I see with solar kilns is the temperatures are inconsistent and dependent on the sunshine, or lack thereof.
> At night, there is nothing. So the wood temp varies hour to hour. If you have a massive stack, the stack will retain (most of it's ) heat overnight, but smaller stacks can't do that as easily. And then...what happens the next morning if you have a number of cloudy days?
> 
> I try to keep my stacks at 90 degrees 24/7 and a bug kill cycle towards the end and back to 90 again for a last day and slowly drop off back to room temp for a number of hours before removing the wood at the very end.
> ...


As far as I have read, which I'm sure the region you live in can change this, you can have absolute control but it requires attention. You have hatches you can open to regulate the temperatures on a daily basis. As well as a timer on the fan, which was recommended to shut off an hour before sunset... I watched and read a from a great source that I can't think of now. 

I think I am going to build one eventually, and there is no reason I couldn't add a heater to it!


----------



## aardvark (Sep 29, 2011)

I understand having ventilation control, but night times and a 2 or 3 day stretch of cloud/rain days can't be controlled. I understand that on cloudy days some solar gain still happens, but I'm curious just how much.
And as said I like to maintain that 90 degree temp without fluctuations.

Here we are living in what's classified as a ''temperate rainforest''..... Lotta rain days.


----------



## bmarshall9686 (Jan 17, 2016)

Yeah there is enough moisture in the air to be considered a rain forest


----------



## Tennessee Tim (Dec 15, 2010)

Very few IF NONE in a solar kiln can maintain the kill temp at the center of wood to be effective... they're not designed to...they're designed to speed up a drying process which works like ADing but gathers heat faster and keeps wood from gaining MC at night or bad weather. I think they're grand in how they cycle the wood...kinda like squeezing a sponge and relaxing it, the MC releases better and works it's way out sooner from the center, this cycle also reduces stress internally in the wood as it dries.

Most solar kilns have a fan/electric source that operates flaps and vents....yes there are some that are ALL Manually controlled.


----------



## bmarshall9686 (Jan 17, 2016)

I have only seen the manual kind but automated sure sounds nice. I think my process would be to solar kiln it, and towards the end of the cycle introduce a heat source to seal the deal.


----------



## Tennessee Tim (Dec 15, 2010)

Here's their link.... http://timbergreenforestry.com/Solar Cycle Kilns.html .This group has the most informational site I've found that makes sense and lines up with nature also. It's been a while since I've read their articles, yes more than one, I don't recall if they get a bug killing heat somehow or if they do or do not attempt....DO NOTE: they pre-dry down to 12% in a accelerated set-up in this building prior to solaring down to 6%.

After relooking at their simple plan Aards is fairly close except electric (note their moisture release) BUT they start at a differ MC when finalizing.


----------



## aardvark (Sep 29, 2011)

Well, heres one version of a solar kiln.
Drying chair legs on the blacktop driveway in July...and cooking breakfast at the same time.
Note:
The temp was over 150 degrees and my breakfast was coming along fine. (It was hotter in my car.)

Ha!


----------



## bmarshall9686 (Jan 17, 2016)

This is great! You do know we all are neighbors and I look forward to hearing from you all.


----------



## jessesnowden (Mar 15, 2015)

Hey Tim,

So in a solar kiln what do you prescribe as a good drying regimen? As far as what temps you should shoot for and at what MC. I'm in seattle area, drying 12/4 white oak slabs.


----------



## Tennessee Tim (Dec 15, 2010)

jessesnowden said:


> Hey Tim,
> 
> So in a solar kiln what do you prescribe as a good drying regimen? As far as what temps you should shoot for and at what MC. I'm in seattle area, drying 12/4 white oak slabs.


Refer to the link on post #18. I'm not up on the drying schedules and you should study them prior ruining slabs....the thicker the more subject to stricter guidelines. I'm good for most basic study of drying BUT specs and guidelines are TOO MANY and I only keep in my feeble mind things I need or bookmark the page...LOL!!! Sorry:grin:


----------



## jessesnowden (Mar 15, 2015)

Thanks for the direction! After following that link and a few more from that site I think there is a pretty solid pattern. Most people are shooting for between 120-150° opperating temp during the day. Keeping the kiln relatively air tight for the first few weeks to avoid drying too quickly and putting defects in the boards. Then opening up the vents a bit to allow a bit more air circulation. There were 2 different posts from people in wetter climates that were having problems with mold doing this. So to aid with that they kept fans on 24/7 and opened the vents up at sun down to get rid of that 100% humidity hanging in the air all day. 

Once MC is below 20-30% most people crank up the heat by keeping it as air tight as possible until they reach >10% MC. 

So that's what I'll try to do I guess! I'm worried about mold being in seattle. Humidity even in the summer is pretty high on the coast. So I think instead of setting up solar powered fans I'll just use a large volume floor fan for now. Thanks for getting that ball rolling Tim


----------



## Tennessee Tim (Dec 15, 2010)

Double check with Dr Gene on www.woodweb.com also. He is one of the top drying specialists and he also drew up I think the Virginia University Solar Kiln package. His knowledge would be of great value to any dryer. You can search their site also for threads regarding solar kilns.....as with most there's many opinions about them.

I'm not sure about the high temps in the beginning BUT I haven't viewed the documents in a while...they may also be the temps in the heat chamber and not necessarily what is at the wood in a flowing/circulating manner. Above 130 is bug killing IF it can be sustained to the core of the lumber for X # of hours....MY belief is minimum of 24 hrs...but others say less.


----------



## bmarshall9686 (Jan 17, 2016)

If it doesn't kill them at least it will annoy them?


----------



## Tennessee Tim (Dec 15, 2010)

OK....I've done some quick reading and this is what I've quickly gathered BUT there's more tidbits that needs to be with this I'm sure.

Timbergreen Solar kiln drying states they are "PRE"-drying down to 12-15% MC approx. THEN SOLAR drying down to 6% [email protected] this % starting the solar it's almost impossible to destroy the lumber at those temps IF all is going directly to the lumber.

IF I read Gene's Virginia Tech solar kiln correctly they're discussing going in green and there are schedules of MC loss to guide by and IF NOT done correctly you can get casehardening, checking and other issues from high temps and/or wrong/fast MC drops... NOTE....each species and thicknesses have variables in the temp and speed dried, PLEASE get specs for type you desire to dry.

As I've always said...SPEED KILLS....LOL!!!


----------



## bmarshall9686 (Jan 17, 2016)

My plan is to take it down to 20%Mc and then solar kiln it, slowly. I just need to build it now... I told my wife I would make something to hold wood that looks a little more presentable than a blue tarp. So I figured might as well make it a small kiln at the same time.


----------



## bmarshall9686 (Jan 17, 2016)

It is a bit long but this is one of the best videos explaining solar kilns.


----------



## Tennessee Tim (Dec 15, 2010)

Here's a good link on dying and different conditions caused and why during drying on woodweb.com http://www.woodweb.com/knowledge_base/Humidity_Control_Warping_and_CaseHardening.html

It also has links to more in depth reading written by the wood doctor Gene. I've talked/discussed with Gene several times, VERY knowledgable AND HELPFUL. IF it's happened he's probably seen it. Thanks Gene!!!
Yes this is the competitors website BUT WE are here to help each other!!! PLEASE mods don't remove!!!


----------



## djg (Dec 24, 2009)

I know his is an old thread, but it has a lot of useful information for someone like me just starting up a kiln. Thanks TN Tim for taking the time to put it up here. (I need all the help I can get).


----------



## Tennessee Tim (Dec 15, 2010)

Your welcome djg. That's just a drop in the bucket but most of the main basics.


----------



## bikeshooter (Nov 5, 2010)

bmarshall9686 said:


> I suggest using a hair dryer about 6 inches away, you can dry 1 bf in about 6 weeks


Now that's funny! :vs_laugh:


----------

