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Kiln dried, air dried, MCs and EMCs

Started by GeneWengert-WoodDoc, February 11, 2013, 06:15:47 AM

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GeneWengert-WoodDoc

I suggest that we do not use the term "kiln dried" or "air dried" when referring to hardwood lumber, as there is no traditional or legal definition associated with those expressions. There are many kilns running at a maximum of 115 F.  They do not kill insects.  There are many that have lumber over 10% MC.  likewise, air dried lumber stored at a dry condition (I store mine in my attic) will be under 7% MC and will not have decay or insects due to the high summer heat in my attic.

So, we should sell lumber based on its MC level and not KD or AD.

Although KD kills insects, once the lumber leaves the kiln, it can be infected with the powder post beetle.

Note that for softwoods, KD means (according to the grading rules) under 19% MC at the time of grading and that the wood was heated to over 160 F.  Note that this sets the pitch real well.

Now, AD lumber can be quite dry.  Check out your local EMC using
http://www.fpl.fs.fed.us/documnts/fpl run/fplrn268.pdf
For example the average monthly EMC in Columbia, SC where I am now is 11.8-14.0.  At home in WI, it is 12.5-15.7. More humid than SC.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

scsmith42

Gene, you make a good point; I would think that there are three things that a woodworker should be concerned about:

1.  Is the lumber suitably dry for their project needs (6 - 8% for indoor, 16% give or take for outdoor.
2.  Was the lumber dried in a manner that prevented drying related defects,
3.  Is the lumber sterile?

Many of the period furniture restoration folks swear by air dried lumber, as they feel that it works better than kiln dried.  From my own observations, lumber dried in low temp DH kilns seems to work similarly to AD lumber, versus lumber dried at higher temps seems a bit more brittle.

Many of the period furniture guys also say that black walnut that is AD has a more robust color that BW that is kiln dried; and that pigments can leach out of the BW when kiln dried.  Personally, I've not seen a difference in BW either AD or KD in a DH kiln, and the water coming from the unit is clear no matter what species is in it.

One problem with the KD designation is marketing and educating the customer.  Many of the home woodworkers are not familiar with the benefits of sterilization, and many of the AD customers are not aware that low temp drying produces a product that works similarly to AD material.

The biggest pest problem in my area is powder post beetles.  They seem to love oak and if I don't sterilize the lumber the tell-tale exit holes will show up in almost everything.  Do you know if PPB's a problem everywhere, or just in certain areas?
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

Jay C. White Cloud

I can speak to the PPB's topic.  They can be dealt with in a number of ways, including spraying down the wood with just a diluted borates solution in a bug sprayer.  There are also several botanical base sprays but they break down quick in heat and/or UV.  Wood is safe after in reaches a MC below 20% as the different coleoptera (beetles) like powder post, death watch, stages, etc. can't maintain viable eggs with out higher humidity.  In most cases in barns and furniture it is just the larva leaving the would and not a new infestation.   Sometimes in barns when the MC raises because of livestock you may see a re-infestation.  Any type of finish, even a light spraying of furniture polish will deter these different species.

Regards,

Jay
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

Tree Feller

I think you make a very valid point, Doc, but it will take a lot of educating for it to become standard practice. Most hardwood retailers sell their lumber as "kiln dried" and it is actually stamped on construction lumber even though the MC is 19%.

The ones who would probably welcome your suggestion are the hobbiest woodworkers who process their own lumber. Most of them tout "air dried lumber", primarily I think, because they have no easy way to kiln dry their own. Eliminating the designation kiln dried and air dried would eliminate a lot of discussion about which method is better.

Cody

Logmaster LM-1 Sawmill
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woodmills1

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mesquite buckeye

Quote from: Jay C. White Cloud on February 11, 2013, 09:43:07 AM
I can speak to the PPB's topic.  They can be dealt with in a number of ways, including spraying down the wood with just a diluted borates solution in a bug sprayer.  There are also several botanical base sprays but they break down quick in heat and/or UV.  Wood is safe after in reaches a MC below 20% as the different coleoptera (beetles) like powder post, death watch, stages, etc. can't maintain viable eggs with out higher humidity.  In most cases in barns and furniture it is just the larva leaving the would and not a new infestation.   Sometimes in barns when the MC raises because of livestock you may see a re-infestation.  Any type of finish, even a light spraying of furniture polish will deter these different species.

Regards,

Jay


Mesquite powderpost beetles are active even when our relative humidity drops to 5%. No me gusta eses.


smiley_furious3
Manage 80 acre tree farm in central Missouri and Mesquite timber and about a gozillion saguaros in Arizona.

Den Socling

mesquite buckeye. I may be in Tuscon this week. Do you have a company I might visit? I don't want to bug you personally. I'll have my old dad and wife along but I would like to see your sawing and drying. For just a half hour or so. I'm taking dad down from Phoenix to visit one of his surviving ancient friends.

Jay C. White Cloud

Hey M.B.

You just got weird "buggy beetles," there in the desert, but from what I understand, even that subspecies of Powder Post family Bostrichoidea, don't like the dry stuff very much.  They all respond well to the treatments I described.

Regards, 

jay
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

mesquite buckeye

Quote from: Den Socling on February 11, 2013, 08:12:23 PM
mesquite buckeye. I may be in Tuscon this week. Do you have a company I might visit? I don't want to bug you personally. I'll have my old dad and wife along but I would like to see your sawing and drying. For just a half hour or so. I'm taking dad down from Phoenix to visit one of his surviving ancient friends.

I will be out at the mill in Redington tomorrow and Wednesday if you want to stop by. If you have GPS, that will get you there. Redington is about 5 houses. Let me know if you need more.....
Manage 80 acre tree farm in central Missouri and Mesquite timber and about a gozillion saguaros in Arizona.

mesquite buckeye

Quote from: Jay C. White Cloud on February 11, 2013, 08:43:43 PM
Hey M.B.

You just got weird "buggy beetles," there in the desert, but from what I understand, even that subspecies of Powder Post family Bostrichoidea, don't like the dry stuff very much.  They all respond well to the treatments I described.

Regards, 

jay


We don't leave any sapwood unless we spray with timbore first. I've got a buddy who turns bowls who has trouble with his live edges turning to powder even if they are finished......
Manage 80 acre tree farm in central Missouri and Mesquite timber and about a gozillion saguaros in Arizona.

Jay C. White Cloud

Hey MB,

That has happened on museum stuff too.  The little "blighters," are in the wood prior to the wood being used.  There are different treatments.  What is "timbore," I want to add that to my list of remedies.

Thank's

jay
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

mesquite buckeye

Quote from: Jay C. White Cloud on February 11, 2013, 09:31:02 PM
Hey MB,

That has happened on museum stuff too.  The little "blighters," are in the wood prior to the wood being used.  There are different treatments.  What is "timbore," I want to add that to my list of remedies.

Thank's

jay

Just a brand name for a borate product.
Manage 80 acre tree farm in central Missouri and Mesquite timber and about a gozillion saguaros in Arizona.

Jay C. White Cloud

I tell you what, those borates products are just plan great, stop the "buggies," natural, easy to apply and a fire suppressant to boot...
"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

mesquite buckeye

And less toxic to humans than table salt according to the manufacturer. 8)
Manage 80 acre tree farm in central Missouri and Mesquite timber and about a gozillion saguaros in Arizona.

WDH

This is a very complex topic.  It is also very interesting as nothing is static when it comes to wood.  That is why I love it.
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

Jay C. White Cloud

"To posses an open mind, is to hold a key to many doors, and the ability to created doors where there were none before."

"When it is all said and done, they will have said they did it themselves."-teams response under a good leader.

Schramm

I wish I never would of read this thread as now I am even more lost then before.

Rob

GeneWengert-WoodDoc

The lyctid powder post beetle is active from around 30% MC down to about 7% MC, maybe 8% MC.  They prefer the grainy hardwoods for laying their eggs.  Be aware that they are often deep within the wood and can do a lot of damage before they exit.  We see the exit holes.  A treatment applied to the surface will only protect the surface.  Meanwhile, those critters deeper in the wood will go on eating, for a year or more doing a great deal of damage.

In addition to lyctid, we have some PPB brought into the USA that are quite damaging and even like softwoods.  For hardwoods, termites and lyctid PPB are the only insects that attack drier wood.

Borates are very good, but they usually are only surface treatments as the wood is not soaked in the solution so the borates can go through to the middle.  So, borates may prevent a new infestation, but will have difficulty in controlling an existing population that is active beyond the surface.  With some species, we would not want to get dry wood wet again deep into the wood using the borate solution...for example, oak...as that will aggravate checks.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

GeneWengert-WoodDoc

The early fine furniture makers did not have kilns, but after air drying, they brought the wood into their shop in the rafters near a stove, etc. to achieve a lower MC than they were able to get in air drying.  They would not use the wood straight off the air yard.  They were well aware of shrinkage issues as the wood would dry in the customer's home.  Certainly some farmers used air dried wood for tables, chairs, stools, etc. without further drying.  These items would crack, shrink, etc., but would serve their purpose even though they were not what we would call fine furniture.

Let me be clear that ordinary, open air drying is a risky process, as you can get staining, checking, splitting and warp, depending on the weather.  For that reason, I like sheds for air drying, as the sun and rain, and sometimes wind, are no longer big issues and so quality is improved.  Likewise, in a kiln or predryer, we control drying conditions in order to prevent these defects.

There are a few times when air drying has an advantage...such as oak for barrels.   We will have a vanilla flavor develop and have less tannins with 2 years of air drying with rain.  However, with excellent kiln drying, we can get the same quality wood as with air drying.  It is a myth that air drying gives wood that machines better, etc. than excellent kiln drying.  But in kiln drying, we do have people that do not equalize, that over dry, and do not remove stresses.  They may also rewet the wood when it is partly dry and increase warp.  I have worked with three companies that make musical instruments and they cannot see a difference.  When you see today's high quality reproduction furniture, made with KD wood, it is clear that the quality is equal or better.  Our industry has lots of wive's tales and this stuff about AD being better than proper KD is one of them.  Maybe it is because there are some kiln operators who are more concerned about time and money than quality.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

GeneWengert-WoodDoc

Regarding borate treated wood, does anyone know if borates can be safely burned?  I am thinking that borate treated wood would be planed and the planer shavings with high borate contents could be made into pellets or maybe burned as shavings.  Is the that safe?  Is the air more corrosive?  What about the high boron content in the ash...can this be put on soil?  Can borate treated wood be composted and used as garden mulch?

As far as Tim-bor being safe, and other borate preservatives, check the link www.prginc.com/Borates/timborlabel.pdf
I am not sure that it is as safe as table salt.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Ianab

QuoteI am not sure that it is as safe as table salt.

Possibly, but eating enough table salt can kill you too....

Only thing I can find about the ash or compost is that high concentrations of Boron can affect plants. Small amounts are probably no issue (it's probably a vital trace element?) but an excess amount left in compost might be an issue and suppress plant growth, which is sort of the opposite of what you want compost to do...

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

mesquite buckeye

Quote from: GeneWengert-WoodDoc on February 12, 2013, 12:12:07 AM
Regarding borate treated wood, does anyone know if borates can be safely burned?  I am thinking that borate treated wood would be planed and the planer shavings with high borate contents could be made into pellets or maybe burned as shavings.  Is the that safe?  Is the air more corrosive?  What about the high boron content in the ash...can this be put on soil?  Can borate treated wood be composted and used as garden mulch?

As far as Tim-bor being safe, and other borate preservatives, check the link www.prginc.com/Borates/timborlabel.pdf
I am not sure that it is as safe as table salt.

Most soils in high rainfall areas either don't have excess boron or are actually deficient in it, so it would be beneficial in these areas, unless you continually dumped your ash in the same place for a long time. Since borate is so soluble, it will move around with the water.....

Usually to get boron toxicity in nature, you have to be in a desert.
Manage 80 acre tree farm in central Missouri and Mesquite timber and about a gozillion saguaros in Arizona.

GeneWengert-WoodDoc

If you burn borate treated wood, do you still have the water soluble borate salt?  I suspect you have elemental boron...is this soluble in water?  If so, how long before it gets into ground water and then into drinking water.  Cities have deep wells, but many people do not and rely on clean ground water.  Boron is a health issue for young children and pregnant women.  When you spread the ash, the boron is in extremely high concentrations...ash is the mineral part of wood with no wood left in it.

If you sand borate treated wood, what are the issues for the sanding dust?

Spreading wood ash is known to be an environmental issue and I do wonder if spread ash with boron is even more of an issue.  In WI, a special permit is required for spreading ash, but of course not for someone putting ashes on their garden every year.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

scsmith42

Quote from: GeneWengert-WoodDoc on February 11, 2013, 11:57:58 PM
But in kiln drying, we do have people that do not equalize, that over dry, and do not remove stresses.  They may also rewet the wood when it is partly dry and increase warp.  I have worked with three companies that make musical instruments and they cannot see a difference.  When you see today's high quality reproduction furniture, made with KD wood, it is clear that the quality is equal or better.  Our industry has lots of wive's tales and this stuff about AD being better than proper KD is one of them.  Maybe it is because there are some kiln operators who are more concerned about time and money than quality.

Gene, thanks much for the insight on this.  Are you saying that there is no difference in properly dried lumber, irrespective of whether it was dried in a Solar, DH, conventional or vacuum kiln (I'm excluding the ultra-high kilns)?  If so, that is good information to know.
Peterson 10" WPF with 65' of track
Smith - Gallagher dedicated slabber
Tom's 3638D Baker band mill
and a mix of log handling heavy equipment.

SwampDonkey

I will also tell ya that 'most' softwood kilns here in New Brunswick do not get the core up to the 160 F. Only a small number and I believe mostly Irving mills. Irving supplies Home Depot in Canada their lumber.
"No amount of belief makes something a fact." James Randi

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2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

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