Kiln dried, air dried, MCs and EMCs

GeneWengert-WoodDoc · February 12, 2013, 01:09:44 PM

Yes, that is what I am saying, but to repeat, not all the kilns you mention would be properly operated by all operators. I also must say that wood issues can result in defects that are not affected by drying procedures.

scsmith42 · February 13, 2013, 09:08:50 AM

Quote from: GeneWengert-WoodDoc on February 12, 2013, 01:09:44 PM
Yes, that is what I am saying, but to repeat, not all the kilns you mention would be properly operated by all operators. I also must say that wood issues can result in defects that are not affected by drying procedures.

Understood - thanks.

mesquite buckeye · February 13, 2013, 10:33:43 PM

Quote from: GeneWengert-WoodDoc on February 12, 2013, 09:00:50 AM
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.

If the wood is burned, you should still have the oxidized form, unless you are making charcoal.

kderby · February 14, 2013, 01:05:24 AM

Thanks for bringing this up. I have a good commercial kiln. I also appreciate air dry. I tell people the kiln kills the insects, speeds the drying process and can set the pitch. Much of what I sell does deserve the insect treatment. Moist of what I run is a heat treatment process more than a kiln drying process. I still call it kiln dry.

I regularly encounter the idea that kiln dry means the lumber will stay straight. People just love to think kiln drying leads to a better product. I remind them that the Stradavarius (sp?) violin was not made from KD lumber.

The kiln is not a miracle machine. In my woodworking experience, air dry lumber seems to have a nicer feel than the cooked material. All of the material goes to EMC anyway. Still, people ask with a hopeful look, "Is the lumber Kiln Dry?"

Kderby

SwampDonkey · February 14, 2013, 06:25:38 AM

I find that kilned hardwood will chip out easy around pilot holes. If you push a threaded rod through a pilot hole, when it emerges it can splinter. Always have to run a countersink bit at the exit of the holes if your using something that is disassembled and the hole is only a touch oversized and it's not friction fit.

GeneWengert-WoodDoc · February 14, 2013, 01:04:36 PM

I would suggest that low MC (under 6% MCe) wood will chip, as you described and not necessarily KD wood.

However, if the kiln uses temperatures in the main part of the schedule over 160 F, we do see some brittleness in the wood that does not go away. Also, if the kiln uses a very low EMC (50 depression which is about 3% EMC), at least the outside of the wood which is where we are machining, will be over dried and brittle. A good kiln operation would avoid these extremes, but not all kiln operations do.

mesquite buckeye · February 14, 2013, 01:24:00 PM

Quote from: GeneWengert-WoodDoc on February 14, 2013, 01:04:36 PM
I would suggest that low MC (under 6% MCe) wood will chip, as you described and not necessarily KD wood.

However, if the kiln uses temperatures in the main part of the schedule over 160 F, we do see some brittleness in the wood that does not go away. Also, if the kiln uses a very low EMC (50 depression which is about 3% EMC), at least the outside of the wood which is where we are machining, will be over dried and brittle. A good kiln operation would avoid these extremes, but not all kiln operations do.

I've had air dried hardwoods chip out too.

SwampDonkey · February 14, 2013, 01:27:41 PM

Gene, the wood I've used is no where near that dry. I don't have a meter, but it sits for months in an unheated warehouse so it's closer to 16%. And also I would have no idea who the operator was or if they know their stuff. I'm in NB, Canada and the wood comes from as far as Ohio and probably Ontario and lots from right here. Some comes in green and some all kilned. The place has their own kilns for the green stuff. They are suppose to be all certified up here. But if CSA is any indicator of the integrity of the certification, than it's not worth beans.

mesquite, are you talking about holes that are tight fitting or loose? I'm talking loose, but not sloppy loose. I the bottom line is to counter sink to be sure. I notice in particular on bench seats made by loom makers the holes are all sunk.

mesquite buckeye · February 14, 2013, 01:33:36 PM

Just from drilling. Same problem on the exit side sawing crosscuts, even with a sharp blade unless I go really slow. My air dried stuff is probably 5% moisture, as our average RH is probably 20% here. Perhaps it's just so dry the wood is embrittled. Don't know..... ??? :

???

Ianab · February 14, 2013, 01:36:25 PM

QuoteI've had air dried hardwoods chip out too.

In a desert environment you could get air dried wood down to ~5%. Abusing it in a poorly operated kiln to get it there just makes things worse.

But heck, sometimes wood just chips out because it can. :D I've had air dried wood at 12-14% chip out in weird ways.

Ian

Edit: You replied with the 5% air dried comment while I was typing :D

QuotePerhaps it's just so dry the wood is embrittled

. This is certainly possible. Moisture content certainly affects how wood behaves.

SwampDonkey · February 14, 2013, 05:26:49 PM

You get tear out on any piece if you don't use backer board under the piece, the pressure as you thin away the wood near the exit will tear out any wood if not set up right. Even plywood. On the sawing, you need a thin Japanese blade for fine wood working. They cut on the pull upward, not on the force downward. The blades in them are a consumable, toss'm when the teeth go and replace. Kinda like the idea of a hack saw, as far as disposable goes. A regular skillsaw or hand saw is just for roughing.

So, now I know we were talking about something different. ;D

mesquite buckeye · February 14, 2013, 06:25:24 PM

Quote from: SwampDonkey on February 14, 2013, 05:26:49 PM
You get tear out on any piece if you don't use backer board under the piece, the pressure as you thin away the wood near the exit will tear out any wood if not set up right. Even plywood. On the sawing, you need a thin Japanese blade for fine wood working. They cut on the pull upward, not on the force downward. The blades in them are a consumable, toss'm when the teeth go and replace. Kinda like the idea of a hack saw, as far as disposable goes. A regular skillsaw or hand saw is just for roughing.

So, now I know we were talking about something different. ;D

Even backed up..... still happens if the wood is brittle enough.

A sharp chopsaw is ok if you are slow enough on the cut..... Some of the more brittle stuff chips anyway....

Jay C. White Cloud · February 14, 2013, 06:35:03 PM

Hey MB,

I perked up when I heard S.D. mention Japanese saws, a specialty of mine. I know when I do use dry wood, (unusual for me as I build green 90% of the time :D) like say "Lace Wood," or some "case hardened" tropical, if I use a good japanese saw there is zero chipping. If you score the cut and use the pull saw. it just can't happen. Just my two cents...sorry to get off post topic.

Regards,

jay

SwampDonkey · February 14, 2013, 06:36:28 PM

Nothing is fool proof. But anyway, my original post was talking about pushing a rod in the hole, not while drilling the hole.

mesquite buckeye · February 14, 2013, 06:57:59 PM

Fine, I'm going back to Quicky Quiz Jackpot to pout.

LeeB · February 18, 2013, 06:41:36 AM

I think the lack of chipout with a Japanese saw as compared to a western saw is due to the ultra thin blades and lesser set, not the direction of cut. You stilll have teeth exiting from the board. The tooth geometry may also be involved.

SwampDonkey · February 18, 2013, 08:07:12 AM

By making the cut on the pull your pulling the fibre toward wood and not toward air. Like a drill press, if you drill against a backer board instead of over a hole, it doesn't tear through. And yes, to the other things as well. There's always something to add if you want to analyze it long enough. ;D Now with the drill press, if you exceed the depth and make a hole into the backer, your next hole is going to tear. Back to square one. ;)

LeeB · February 18, 2013, 11:34:59 AM

You get the tear out when the blade exits the wood, it just exits on the side facing you with a Japanese saw. Push cut or pull cut does the same thing in that respect. Has to be blade thickness.

Jay C. White Cloud · February 18, 2013, 11:43:27 AM

Hi LeeB and SwampDonkey,

Your both right in a since. It does have to do with set and tooth geometry. Lee your also correct about, push or pull, it can still splinter wood either way.

However, what S.D. is getting at is the technique you use with a Japanese saw can mitigate this, or if your trained in there use by someone that actual makes the saw, you should have absolutely none. I can cut through any species of wood timber, with several different types of Japanese saws, and the tear out is about zero. If you score the cut, as you should for crucial cuts, it is zero.

Regards,

Jay

LeeB · February 18, 2013, 11:57:47 AM

If you score the cut before using a Western style saw you get no tearout. As you said, it's the technique, not just the saw. Just for the record, I do prefer the Japanese style saws.

bedway · February 18, 2013, 12:11:47 PM

For what its worth, after woodworking,cabinet making for over 35 years my preference is to work with air dried wood. It is easier on the equipment and is more stable than wood that has been kiln dried. Seems to take finish better in my opinion.

Jay C. White Cloud · February 18, 2013, 12:13:21 PM

I hate getting off post... this is good info, shouldn't this be on it's own post? I'll do it if others think we should so this info isn't lost here under drying wood.

By the way I still like using only air dried or green wood.

Regards,

jay

mesquite buckeye · February 18, 2013, 12:42:18 PM

wait_smiley

GeneWengert-WoodDoc · February 18, 2013, 12:45:57 PM

If air dried wood appears to be more stable, it is because you have it closer to its in-use MC, which reflects well on your operation. Many tests have shown no difference between AD and KD if at the same MC, and if the KD has not been over dried or dried over 160 F and it has been equalized and stresses relieved.

Jay C. White Cloud · February 18, 2013, 01:05:01 PM

Sorry Doc,

I was going back to edit what I wrote, but you beat me to it. I like working in green wood or air dried, as I said. However, Doc is more than correct, there is absolutely no difference between AD and KD would as long as the drying process of the "kilning," was done well.

Another way to look at it, just about anyone can AD wood. I find very few KD wood that is of the quality I am accustom to in the wood I work, that could be me, but seems to be the case with many Furniture Makers and Luthiers I know as well.