So Much Rain - A Moisture Question.

[John Scane]

Here in So Cal the weather is usually good for woodworking in a garage or large open shop but lately it has been a little wet out . I have a shop that is basically open to the outside most of the time with no heating or a/c. My shop is very close to the ocean also. Usually the wood in my shop is somewhere around 10 - 13% moisture content. Obviously lately it's been higher. My question is: how do you guys deal with having shops that are "open" and do you work when it is very damp out ? I have always worked in a garage or open shop and have not really had any problems with furniture moving too much once I bring it inside. How concerned are you guys and what do you do ?

Another question is, what websites might have a moisture content chart for working different woods.

Thanks,
John

[lou sansone]

dear john

glad you asked this question... I am sure that some well meaning individual will say that if your wood was kiln dried then it is as dry as it needs to be. Or better yet they will say the the wood has been air dried for 10 years and this means that it is "really dry". Your question points out one of those real eye openers for ww's and that is if a kiln and low RH can take the moisture out of the wood ( usually within 60 days ), then why would someone think that a humid environment like yours would not put a lot of that moisture back into the wood. Anyway so much for my sermon on wood and moisture.

There is no way to prevent the problem that you are discussing without "climate control" , there is just no way!! The only exception to this would be to pack up all your stuff and move to arizona!


If, and I say if, you were to buy freshly kiln dried wood and use it within about 2 weeks then you would be ok, but it you let it sit around in the moist climate then you are going to move that 6% toward the EMC of the wood, which in your case is 13% or more. @ 13 % you are going to get into trouble with certain types of construction.

Bottom line is learn to live with it, or keep the door closed and climate control your shop. What I do for my shop is to keep it heated and have the wood I am working on inside my shop. The moisture is @ 6% in the shop wood and 10 to 12 in the other building. I keep about 3000 bd feet in my shop at all times and another 6000 in another building that is dry, but not heated. I may install a dehmidifier in the other building this year.

[Jim Becker]

Within reason, the exact MC level is of less concern than the consistancy of it within the material that goes into a particular project, assuming you are building with techniques that account for wood movement...which everyone should do without question. I'm saying that a little differently than Lou, but essentially we agree, I believe.

I've never been concerned with having lumber at "6%" MC. In fact, most of the air dried material I use...and most of the material I use is just that...is more typically in the 10-12% range. That's pretty much normal for my area. Even the KD stuff on my racks is near the lower end of that once it's been "in stock" for awhile. I acquire material when the "getting is good" and am still working off the stock from my on-site milling session back in 2000. So whatever MC it is...is what it is...and I build accordingly.

[Mark Singer]

John,

So your getting rain! WOW! We are too.
Since all the wood changes together, I never found it to be much oy a problem. It takes a while for the wood to attain the ambient moisture. If you design for wood movement, I think you will be ok. When it goes indide it will all move together. Of course cross grain will move much more.

[Ted Shrader]

John -

From the looks of the news reports here, you are lucky to "only" have to worry about moisture content of your wood and not that of the ground.

Watch your construction techniques and allow for wood movement. Always a good policy anyway, no matter the prevailing climate. My F-I-L in Kansas (dry) many years ago, made some walnut furniture with very nicely fitting drawers. A couple of months after he delivered it to us in Charleston, SC (wet), the drawers were dragging. The sides were too tall. The wood had moved enough to cause the to drag on the tops the drawer openings.

Keep your stock in a dry location and build with movement in mind. Before the days of AC, the only climate control was a fire of some sort. Wood moved with the seasons - still does.

Ted

Ted

[lou sansone]

All of you have made good points that for the most part I agree with, but I have found from hard experience that once you get past 10% wood really will move quite a bit when placed in a centrally heated house. Ted is correct about antique furniture, but since this is sort of my specialiaty I can say that more antiques have been damaged since the advent of central heat then the previous 200 years ( discussing 18th century stuff ). Take a look at 18th century furniture and you will find lots of examples of cross grain construction that would make modern the ww cringe. But it was not a problem back then due to the fact the wood would not get down to real low moisture content. As you have all correctly pointed out, taking into consideration the wood's movement is critical to building furniture that does not crack in the winter when it shrinks.

I offer just 2 real life examples. A tall case clock and a Highboy



Take for example tall case clocks that normally have a very slight lip ( 1/8" to 1/4" ) on the pendulum (sp) door that is usually about 8" wide. When you go from say 12% moisture to 6% ( which you will in the winter in New England ) that door will shrink about 1/4". Guess what? Now you can see a gap between the stile and the door lip. Yea, you can make the lip wider to get around this, but it doesn't look quite right.

For my second example take a look at how a highboy's lower case is constructed. Queen ann legs have the sides morticed into them. If you are not real carefull with glue and such you will get cracking on the sides in the winter, because of cross grain construction. Even jeff green who has built hundreds of these has found this to be such a problem that he recommends "Pre-compressing" the sides prior to glue up for just this reason.

sorry to ramble and please do not take offence at my reply. I wish when I was first starting out ww that folks explained this better to me. It would have kept me from making a lot of junk.
lou