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Moisture Meters and Sensors

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Naniana Bampo

Joined
Aug 8, 2013
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Denmark
Hi there, I'm looking for a moisture meter for my work and by now all I found is this www.aquar-system.com/. But before making a decision I would like to see some other producers so that to compare meter's characteristics and prices. So please, drop a line and a link to it if you know some other stuff like that.
I would appreciate any help! Thank you in advance!
 
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Your link is to an industrial site for equipment used in commercial drying operations. Simple hand-held meters do just fine for hobbyist and small shop use. They come either "pinned" or "pinless". I have and use both as I harvest, saw, and air-dry my own lumber for flat work.

There are a number of makers. I use units made by a Canadian company -

http://www.electrophysics.on.ca/e_index.htm

However, I don't bother when it comes to turnings. I either turn to finish and let them move, or I rough and let them sit for a year or more; I'm just not in such a rush to finish a particular piece. :cool2:
 
I have a 2 pin pocket sized Lignomat I have been using for about 15 years.
Paid under a $100 way back then.

The pins make holes so you have to have waste areas. I use the tenon on roughed out bowls.
I also measure the ends of turning squares that I air dry.

I return bowls when they measure less than 10%.

I used the weighing method for quite a few years but the moisture meter works great for bowls with tenons and when I want to turn a bowl I just pull rough outs and test them. A lot more convenient and less trouble for me.
Mine looks like this one.
http://www.lignomatusa.com/MoistureMeter/moisture_pin_meters_mini.EC.htm

I sometime use it to measure moisture content of wood before I do demos so I can tell the audience the MC.

Al
 
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Bill Boehme said:
I think that weighing the wood is much more practical and far less costly than an expensive moisture meter.
Click to expand...

I'll have to agree with Bill on this.....with some clarification.

I've been using the exact same Lignomat pinned moisture meter as Al Hockenberry for about 20 years. What I've found is the hand held unit is great for getting an initial MC (moisture content) reading. From there, you can come up with a "game plan" for roughing and drying a bowl block. It is important to understand that not all bowl blocks, and roughouts will require the same techniques in seasoning to stabilization.

The trouble with using the moisture meter throughout the seasoning process, is that you only know what the MC is close to the surface. This might be OK in some cases, but will be trouble at other times.

The only true way to know for sure that a roughed bowl has stabilized the MC, is by recording monthly weighings. Normally, three months of unchanged weights is an indication of stabilization......but, that is subject to other things, so is not an absolute.

Denseness of the wood species, time of year, how controlled the environment where seasoning takes place......all these things will need to be taken into account, as well. My seasoning takes place in an uncontrolled environment (above 40oF up to around 90oF in the summer), so seasoning takes place more slowly during the winter months. Example: For a dense species, like Cocobolo, I might want to record a few more months of unchanged weights to be sure stabilization has actually occurred. This is especially true during the winter months.

My recommendations would be to get both a hand held moisture meter, and a scale. The combination of both, IMHO, when used to their specific advantages......gives the best results overall. :cool2:

ooc
 
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I should add that I air dry bowl by putting them in paper bags, changing the bags for dry ones every day for a week until the bags are no longer damp.
Then leaving them in the bags 2 months then a shelf for 4-8 months....

Rough out walls are 1" think to 1.5 " thick. I turn the bottom a 1/4 to a 1/2" thinner so that the tenon doesn't add a lot of thickness.
The bottoms don't warp much. I test on the tenon
On turning squares I coat the end with wood sealer and test through the end grain.

If you coat bowls with wood sealer. The moisture meter may not be as reliable.
It won't work well on end grain bowls as the bottom would dry faster than the walls.

My goal is to have a bowl that is going to look round for its lifetime.
My experience is that getting below 10% on the tenon works for me.

If I am turning pieces that I want not to move. Lidded boxes, ball in a ball
I pop the moisture meter drive pieces through a couple of microwave cycles just to be sure.
 
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Naniana Bampo said:
Hi there, I'm looking for a moisture meter for my work and by now all I found is this www.aquar-system.com/. But before making a decision I would like to see some other producers so that to compare meter's characteristics and prices. So please, drop a line and a link to it if you know some other stuff like that.
I would appreciate any help! Thank you in advance!
Click to expand...

Hi Naniana Bampo........

Sorry, but we got a little side tracked with discussion.......😱

As per your request, here is a link to a few moisture meters currently available at woodcraft supply:

http://www.woodcraft.com/search2/search.aspx?query=moisture meter

good luck.....

ooc
 
I'm with Al on this one, I've used a pinned Lignomat for about 5 years now with great success.

It cost around a $100.

Happy Turning
Tom
 
More Than Surface Readings

The Electrophysics CT100, the pinless meter I use, "reads" to a depth of 1". Thus, when applied to either side of the wood, it gives accurate readings for 2" of thickness; more than enough for most roughed out turnings.

The readings will, however, be skewed if wax sealer is applied or the wood has been soaked in detergent (soap-soaking) or alcohol. Most waxed bowls can still be "read" through the tenon if one is used.
 
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Well, I don't use a moisture meter because I turn to final thickness and let the bowls warp. They are dry in 10 to 14 days. The thing is, after years of turning, I can pick one up and tell by the feel if it is dry. Mostly if it is cooler than other pieces, it is still drying. When it no longer is cool, it is done. Most thicker pieces will be mostly dry in 6 to 12 months. Just turn a bunch and let them dry, and try to keep a rotation going, some rough turning and some finish turning. Some do bag their pieces, some anchor seal (or other sealers) and stack them so air can flow through. Some make dehumidifier kilns to speed up the process. Drying is a separate art, and changes for each species of wood, and for each local climate.

robo hippy
 
Something to consider.......

The ultimate goal is stabilization, or that point when the moisture content within a piece of wood closely matches the ambient atmosphere. This percentage of moisture content will not be the same at different global locations, for the exact same piece of wood. This is why some wood turnings are adversely effected by moving it from it's place of origin, to some other global location......from dry to humid climate, or vise versa.

What is happening during the seasoning process, is a loss of water to the point where it's stabilized to it's local environment, or atmosphere. That loss of water is positively, and accurately measurable.....by it's weight over time. Although using a moisture meter gives an indication of moisture content, this measurement is only accurate at the surface, and location around the circumference. For some applications, surface measurement of MC is good enough, but at other times, it isn't. A dense roughed bowl with 1" walls, might be metered at 10% MC at the point of measurement, but might be 18% MC at the interior. Finishing this bowl will be a gamble. A nice finished bowl might be had, or it might not. Even if the bowl looks good at the point of origin, it might crack up and be a complete failure if it's moved to another global location. Stabilization must be as complete and thorough as possible, if that bowl is intended to withstand the test of time.

Stabilizing MC by weight over time, is a much more accurate way of determining that stabilization has indeed occurred. For many less dense woods, there is much less risk of losing a bowl because the MC was not stabilized in the interior of the wood. For very dense woods, sometimes it takes more time, and more weighings to accurately assess that the MC has stabilized.

ooc
 
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Mark Mandell said:
The Electrophysics CT100, the pinless meter I use, "reads" to a depth of 1". Thus, when applied to either side of the wood, it gives accurate readings for 2" of thickness; more than enough for most roughed out turnings.

The readings will, however, be skewed if wax sealer is applied or the wood has been soaked in detergent (soap-soaking) or alcohol. Most waxed bowls can still be "read" through the tenon if one is used.
Click to expand...

Hello Mark.......

You and I were typing at the same time......😀

If it's true that your moisture meter is accurate to 1" depth, then yours does a better job than mine. I can see how using your moisture meter will determine stabilization at a more trustable rate, than mine would. Is yours limited to 1" at the side of the measurement point, as well? It's been my experience that denseness, and grain patterns effect the MC as well......up to around 4-6%, or more on the same piece of wood, or roughout, at different locations. Unless you take multiple measurements in the interior, and exterior, around the entire circumference, there will still be a margin of error. I can see how that margin of error will vary, but reliance on moisture meter alone will necessarily introduce a certain amount of gamble, in that what you see isn't necessarily a true measurement of what you get.

Still, weight changes are a measurement of the entire water content of the entire roughed bowl, or bowl blank. Water loss is measurable, and is accurate. When that water loss is observed to have stopped completely, through multiple weighings over a time element, the gamble that stabilization has occurred is practically nil.

ooc
 
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For a face-grain bowl, the tenon is likely to be the thickest portion of the face grain and thus last to reach EMC so once that area is determined to be at EMC, the rough should be good to go.

If I had a scale with the capacity and sensitivity to accurately weigh turnings over the months needed for drying, the continual weighing of roughs and then charting their progress to dry is far more than I have any interest in doing.

When I do a bowl, I rough, wax, mark the month and year on the tenon, and deposit in an available corner, shelf, or bin.

Not something I do a lot of as jars and such, being turned end-grain and down to 1/4-3/8" or so, pretty much spin themselves dry during the process. At most they take 2-3 weeks in a brown bag to get ready for finishing.
 
Mark Mandell said:
If I had a scale with the capacity and sensitivity to accurately weigh turnings over the months needed for drying, the continual weighing of roughs and then charting their progress to dry is far more than I have any interest in doing.
Click to expand...

Mark.......

Postal scales are cheap......about $25

I normally have between 50 and 100 bowls being seasoned at any one time. Monthly weighings take about an hour per month to complete and record. If you are interested, I could show you how to do it. It's all a matter of organization, no real problem to do it.

Let me know.

I'm on vacation right now, so in order to access my photos, it'll have to be sometime after next weekend........

ooc
 
odie said:
Mark.......

Postal scales are cheap......about $25

I normally have between 50 and 100 bowls being seasoned at any one time. Monthly weighings take about an hour per month to complete and record. If you are interested, I could show you how to do it. It's all a matter of organization, no real problem to do it.

Let me know.

I'm on vacation right now, so in order to access my photos, it'll have to be sometime after next weekend........

ooc
Click to expand...

Guess you missed it. I'm not interested. I don't turn more than a couple of bowls a year.

Have fun on your vacation
 
I got mine from the stil shop that's the chainsaw one if there is one were you are It was only $45 N Z the size of a match box.

Ian
 
Naniana Bampo said:
Hi there, I'm looking for a moisture meter for my work and by now all I found is this www.aquar-system.com/. But before making a decision I would like to see some other producers so that to compare meter's characteristics and prices. So please, drop a line and a link to it if you know some other stuff like that.
I would appreciate any help! Thank you in advance!
Click to expand...

When you take a reading, you have half of what you should know. The other half is the relative humidity, or at least a rough average for the last week. This is because equilibrium moisture content depends on relative humidity.

I'm a fan of weighing. Not for the sake of weighing, as some seem to be, but for the sake of determining if the piece is at EMC. So I don't bother to weigh and date pieces I know are not ready. I put them on the shelf, turned to ~1/2 to 1" depending on diameter and shape, and look at them when I'm ready to turn to see if it's likely they're ready.

http://i35.photobucket.com/albums/d160/GoodOnesGone/Picture-Package-14.jpg

Shows about an eighth of an inch difference between long and cross grain direction, so it might be. Weigh, lay for a few days, weigh again. Since I have a handle on relative humidity in a couple of let-down places, I can toss fresh turns into the quiet air in a corner of the basement in summer, or outside in the garage. Takes a couple - three months at 1", depending on RH, to be ready. Last one is spent in shop conditions. If I want to push, I microwave a near ready piece.

As you can see from the picture, I also don't believe that bottom thickness means anything. The bottoms of my stuff go all the way to the top. What does make a difference is how broad. Distance to air along the grain is the key. Too far and you want to retard cure rate to keep from splitting.

You may check your stock at any time with that moisture meter, or any other, and half of what you want to know. Or you may concern yourself with only what you need to know.
 
Mark Mandell said:
Guess you missed it. I'm not interested. I don't turn more than a couple of bowls a year.

Have fun on your vacation
Click to expand...

Hey, no problem at all, Mark...........

Having a good time on vacation.......confirmed how terrible a golfer I am! 😀

ooc
 
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