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How to test for moisture content

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Forum topic by amateur posted 02-21-2011 12:23 PM 3493 views 0 times favorited 13 replies Add to Favorites Watch
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amateur

91 posts in 1402 days


02-21-2011 12:23 PM

I have a slab of ash drying in my garage shop. It was cut about two years ago. Measures 44” x 3” x 72”. When can I begin to think about using it and is there any way of testing moisture content without a meter? I don’t want to jump the gun, but I hear it calling my name. If it is still too wet, practical suggestions on speeding up the dry time would be appreciated. Thanks.


13 replies so far

View Bill Davis's profile

Bill Davis

226 posts in 2668 days


#1 posted 02-21-2011 01:40 PM

Yes you can find the moisture content without a moisture meter.

What you need:

A sample piece of the wood cut from the center of a representative board that weighs approx 100gm,
An accurate scale capable of weighing the piece to the nearest 0.1 gm.
A small toaster oven that can be set to run at 212degF continuously i.e. not on a timer.

Procedure:

Weigh the piece of wood to the nearest 0.1gm.
Put the piece of wood into the oven and set the temperature to 212 deg F.
After 24 hours weigh the piece again.
Put the piece back into the oven for one more hour.
Weigh the piece again. If it weighs less than the last measurement put it back into the oven for another hour.
Weigh it again. Repeat this process untill the weight remains the same as the previous weight. That is the oven dry weight.

Now take the original weight and divide it by the oven dry weight. Subtract 1. Multiply the result by 100. The resulting number is the moisture content of the original piece of wood.

Or just get a moisture meter.

If moisture content matters, and it does, then you should have a moisture meter and use it in your shop. How much have you paid for your other tools? It has been said that 90% of all problems with wood are related to moisture. Isnt it worth $100-$200 to have one?

View cranesgonewild's profile

cranesgonewild

344 posts in 1652 days


#2 posted 02-21-2011 04:32 PM

Hey Bill, what moisture meters would you recommend?
I need one as well.

-- I'm a Fungi --

View Nomad62's profile

Nomad62

726 posts in 1702 days


#3 posted 02-21-2011 06:37 PM

I would think it useable by now provided your garage shop is heated. You could take a slice about an inch thick from the edge and put it in your house for a month and see if it moves; if it stays straight you should be just fine. If it warps, twists, whatever (after drying, not right away) then it may require more time.

-- Power tools put us ahead of the monkeys

View Scsmith42's profile

Scsmith42

125 posts in 1421 days


#4 posted 02-22-2011 04:12 AM

RE moisture meters, most kiln operators use meters by Delmhorst, such as the J2000. For a professional grade RF type meter, look into the Merlin’s.

-- Scott, North Carolina, www.quartersawnoak.com

View a1Jim's profile

a1Jim

112817 posts in 2321 days


#5 posted 02-22-2011 04:23 AM

Here are the moisture meters I suggest.

http://wagnermeters.com/woodworking.php?gclid=CNDvq__ZmqcCFUMUKgodNQfn2g

I own the L606 and have found it to be very accurate and very sensitive .

-- http://artisticwoodstudio.com Custom furniture

View bhog's profile

bhog

2177 posts in 1435 days


#6 posted 02-22-2011 04:40 AM

I have never owned a moisture meter and possibly never will.Heres how I was taught and what I do ;sweep off dust etc from the piece in question ,touch your fingure (lightly)to your tongue and streak it on the wood.start counting how long it takes to disappear if it is less than 6 seconds I will use it,if not it needs more drying. Now I realize that way is not scientific or as accurate as a moisture meter,but it comes from a time when they didnt have em.

-- I don't drive a Prius.

View reberly's profile

reberly

172 posts in 1433 days


#7 posted 02-22-2011 04:20 PM

I have at least 3 moisture meters. Between the Wagner pinless and the lignomat, my favorite is the Lignomat DX. It is the most accurate from my experience.
Rich

-- "Big Timber is our Legacy" , http://eberlywoods.com

View Barbara Gill's profile

Barbara Gill

153 posts in 1405 days


#8 posted 02-22-2011 08:13 PM

You don’t say if you plan to resaw or use the piece as is. Unless pinless moisture meters have improved they only measure around 1” deep. So the center inch would go unmeasured. If you use a moisture meter with pins you need to either drive it into the middle of the board or drill holes. Either way you have damaged the piece.
I can’t think of any way you can determine the moisture content with confidence without compromising the slab.

-- Barbara

View a1Jim's profile

a1Jim

112817 posts in 2321 days


#9 posted 02-22-2011 08:30 PM

Hi Barbara welcome to LJs
I don’t know about other pinless moisture meters but when ever I’ve tested mine next to a pin type meter and I’ve found my meter to be maybe even more accurate so much in that on a 3” thick piece of wood if you have your hand under the wood where you reading the meter,it changes the reading showing moisture in my hand increasing the moisture reading on the meter.

-- http://artisticwoodstudio.com Custom furniture

View Barbara Gill's profile

Barbara Gill

153 posts in 1405 days


#10 posted 02-22-2011 11:13 PM

Hi Jim thanks. Wow, it appears that pinless moisture meters have come a long way!

-- Barbara

View SASmith               's profile

SASmith

1635 posts in 1731 days


#11 posted 02-22-2011 11:38 PM

Here is a good diy moisture meter from a simple multimeter by Matthias Wandel. Also check out the rest of his site if you have never been.

http://woodgears.ca/lumber/moisture_meter.html

-- Scott Smith, Southern Illinois

View amateur's profile

amateur

91 posts in 1402 days


#12 posted 02-23-2011 01:44 AM

Thanks for the input everyone. I tried the wet finger test, Brandon, and it took a little longer than 6 seconds. In the end, I will use a meter. My plans for a live-edge desk for my home office depend on accuracy. Impatience has been my greatest woodworking nemesis. Guess I’ll take a deep breath and dive into a couple of the other ten million projects I’ve always wanted to do.

View Dave's profile

Dave

11205 posts in 1584 days


#13 posted 02-23-2011 03:17 AM

Bill now i got a head ache. Do you have to do all that standing on one foot. Buy a meter.

-- Superdav "No matter where you go - there you are." http://chiselandforge.com

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