Measuring Moisture Content of Wood

Thanks.

I'll get one tomorrow, I get their coupons too. The store is a half mile from our house.

The guy at the mill was as entertaining as watching him saw the wood. He was a talker.

Ha...we have a HF bout the same distance fro. Us.

From the picture, looks like he used a bandsaw mill.

Gas powered horizontal bandsaw, probably 40 years old.

The whole place looked very old, but they had some very nice wood in their "showroom".

Wood's been around for a while .

So have we!

Here is an article about using a multimeter to measure moisture content of firewood. I don't know if that would be useful in your case.

MEASURE THE MOISTURE CONTENT OF YOUR FIREWOOD WITH A MULTIMETER

http://www.instructables.com/id/Measure-the-Moisture-Content-of-Your-Firewood-With/

Thanks, I saw that earlier and was going to use it, until I bought a meter this morning. I'll still use this to check the other meter's accuracy.

My goal is not to burn firewood but rather to bring the moisture content to a point of equilibrium before sawing it into pieces to build things.

Since I have 1/2, 1 and 1 1/4 inch thick lumber the drying time will also vary by quite a lot.

It’ll be interesting to compare the two...

Did anyone notice that negative sign on the Fluke meter in the second picture?

When you are in resistance measuring mode and you see a negative sign, that's an indication that you have another electrical source in your measurement path that has reversed the current flow in the meter.

As such, what I believe is happening in the second picture is that the nails somehow are interacting with the moisture in the wood and has created a battery of sorts.

I'd be skeptical of measurements done this way. Hard to say what the true resistance is unless you use a four-wire measurement with a higher voltage than is typically put out by a typical DMM (2.5-3.5 volts although I have seen some DMM's put out upwards of 7 volts.)

Sharp eye! No, I didn't notice. I've been using various kinds of multimeters for over 60 years, and I've never seen (or at least not noticed) a negative sign on any resistance measurement, but what you say is entirely logical.

Thanks for the tidbit!

Looks nice. Mahogany is supposed to be easy to dry/cure/season being resistant to the typical problems of cracks and warping.

That is some very nice wood. If you're in a hurry to get working in weeks rather than months consider making a simple "kiln" from a tarp etc. (time is the best kiln)

In the meantime, you can put some nails into your new wood and put some more nails into some various scrap/s of old wood (similar is best)..take some measurements and see how far off you are from dry wood.

Take a guess at how far you need to go (resistance and days) and start making a graph to keep track of the data and see if your intuition matches your observations.

This is Arizona. In the summertime on our patio, it can easily get to 140F which is the final kiln temperature the wood shop uses.

I'm going to select enough for my first project, a coffee grinder, and put it in full sun on the patio under some 8 ga. aluminum sheets. The rest is in stacked on the east side yard, in the shade after noon each day. I will still want to stabilize it indoors before cutting it to size.

The wood will be seasoned long before I can use it up.

Thanks! Very informative. GA.

The only problem with that is that the first layer boards under the tarp (or tin) needs to be sacrificial, like old plywood or something. It so hot under there, it’ll warp and check pretty bad.

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

https://www.wagnermeters.com/acceptable-moisture-content-wood/

First, I'll need to cut more stickers and re-stack the wood in different stacks. It's all stacked temporarily in the (mostly) shade under a tarp.

I'll compare readings sometime next week, but I do have other things to do.

I'll dry enough for the coffee grinder then store it inside to equalize. I think that will take 30 days total, maybe less to reach equilibrium.

Thanks for all the responses.

Most lumber yards will for a small price kiln dry your timber for you!

Bazzer

I have one but don't use it much. Timber cut into slabs like that will season quite quickly if it has good air movement around it and isn't on the ground or exposed to rain.
Rule of thumb is 1 year per inch of thickness, but it depends on what you want it for.
It will probably be dry enough for roughing out or further cutting after 6-9 months.
Even after years of seasoning, it can still move when it's re-sawn to smaller sizes, or when it's moved to a different environment.
Weight can also be used as an indicator, weigh it every couple of weeks, after a few months the weight will satbilize as it reaches equilibrium with it's surroundings.
Del

Speaking about the moisture content of wood.

I finally tapped a sugar maple about a week ago. I only collected a couple gallons to take home and boil down.

The few ounces collected were well worth the effort.

Nothing better.

My brother-in-law has a sugar bush. They do about 600 gallon/year and when I was about 15-16 years old, on the weekends, I helped them collect the sap. and the end of the day, we'd go into the evaporator shed to warm up. It was heaven, you're chilled to the bone and its nice and warm in there with the sweet small of maple syrup...

In my pre-children days I would make wine as a hobby. I got a recipe for Birch sap wine which I made one year. I have to say it was the worst wine I ever made, it tasted like the smell of wet dogs.

Birch sap wine???.. I never heard of that... lol...

I recall logging out an area with my dad, that had a pretty good stand of Birch, Maple and Beech.

We'd saw down the trees, and it was raining... what the heck?,... then it dawned on us, it's was that time of year to collect sap, we sawed some maple and beech, and the stump and log the sap would be just running out.

I tapped my 3 trees in my yard in Feb. I got enough sap that this has been a 4 gallon year from the 3 trees. It isn't running this week and I suspect the season is over. 4 gallons of syrup will give us enough to share with friends and family. Mine is a very rustic syrup because I use wood to boil it outdoors.

Wow that's a lot of maple goodness.

I too boiled mine over wood in the backyard and yes the flavor is wonderful for it.

This was my first go after years of saying.. maybe next year.

Maybe next year I'll "harvest" more maple water..

Please post a picture when you finish your coffee grinder and keep us posted on relative accuracy of the two moisture measurement tools you're using.

Yes, I will. It may be a while, depending on the wood. I promised Tim, the sawmill guy, I'd send him one too.

(They have a kiln but I never considered letting him dry the wood for some reason)

I've been distracted today, standing up a 25' flagpole in our front yard.

I've gotten some great advice from the members here and the next thing I have to do is restack and sticker* the wood more properly.

*(Sticker: small slats that separate the layers of wood to facilitate ventilation)

It maybe ok in Arizona... but anywhere temperate and putting a plastic tarp over wood is a recipe for rot.
Airflow is what you need.
Del

Air Drying of Lumber - Forest Products Laboratory, by the U.S.Department of Agriculture agrees with you on that.

I will separate and re-stack the boards today. I have a 4'x 4' x .125" thick aluminum sheet for a roof for my "drying shed."

The keys to successful drying are time, temperature and moisture differential from core to surface of the wood.

Rot takes time, moisture and moderate temperatures, up to about 110 deg F.

The Forest Service pub is specifically discussing air drying, which is much different than controlled kiln drying.

With controlled kiln drying, you are taking the stickered lumber up as close to 212 deg F as you can get and contain the moisture to maintain a lumber surface moisture content close to the lumber core moisture content. This reduces warpage and development of cracks. This process goes quickly enough, a matter of hours, so that rot has no time to develop. It also tends to sterilize the wood so you don't end up with fungus or bugs.

The second feature is that the wood ends up more stable in the long run because first, the lignin softens and relieves strains. As the moisture content reaches the lower limit, the heat sets the lignin so that it is resistant to resoftening when remoisturized, which would lead to long term development of warping.

I've not seen a swimming pool used as a lumber pond, but they do some interesting things in Arizona.

It'll get up to 140°F in the back yard for the next 3 months, when it isn't raining or we're having a haboob.⇓

Wasahaboob?

The picture wasn't enough?

Dust storm. The front of which can rise to 5,000 AGL. Visibility can go to 5 feet.

Haboob - Wikipedia

https://en.wikipedia.org/wiki/Haboob

A haboob (Arabic: هَبوب‎, translit. habūb, lit. 'blasting/drifting') is a type of intense dust storm carried on an atmospheric gravity current, also known as a weather front. Haboobs occur regularly in arid regions throughout the world.

Well, the first attempt at stacking was a disaster.

So, I wet the boards.

And built a proper rack. This will allow me to clamp the wood, not just weight it.

Obviously, checking moisture content is in the future.

Here's the stack. It's in an open, unused part of the yard where it can rest, undisturbed. No small task just fishing each slab out of the water and stacking it.

I'll insert some probes tomorrow and start checking moisture. I saved two smaller, cracked sacrificial boards for testing.

Today, I took the weights off my lumber stack and removed the top slab and re-weighted the stack.

With the moisture meter and the DMM I got zero readings. Nada.

The moisture meter reads the palm of my hand consistently around 20% so I assume it's working.

The DMM gave erratic results with the palm test, between 1 and .5 Ohm.

The wood feels dry and the cracking is significant in the slab I removed. I will place it in the shade and see if it warps. By eyeball, it looks flat

My shop is not air conditioned and it's supposed to hit 100°F today, so work, except for the coffee grinder, may have to wait till fall.

I had wrapped a single slab tightly in a tarp. It is still wet with condensed water inside. It may be firewood next fall.

As an aside, I had read that this wood is not suitable for using in a grill and have to agree that the aroma was less than alluring. I had set the stump on fire in order to get rid of it without renting a stump grinder. After it had smoldered for two days, two nice firefighters came to the house to say one of my neighbors had complained that I was burning garbage.

My wife explained that I was simply disposing of some parts of the tree I had just cut down. She pointed out the 3 foot x 18 inch log they had passed by, strapped in the bed of my pickup, on their way to the door. They pointed out that since they had gotten a complaint, I should maybe put the fire out for awhile, which I did. Burning wood in a fire pit is perfectly legal, but since she works for the city and knows the fire chief, and several of the inspectors, I decided to delay further disposal for another time. Since I still have access to municipal dump facilities, the rest is all gone.

When I finish the coffee grinder I will post pictures. However remember, my schedule is flexible.