Moisture Meter Suggestion

[paul2004]

I have a ligo moisture meter. I ordered a load of kiln dried lumber, it arrived at an unexpected time and got rained on. Well, I wanted a meter to measure when it was dried.
It works well, if someone wants to buy a used one, send me a PM.
If someone is interested, I'll look up the model number and figure out a price.

[fishhh4]

It's probably not US-made. I have the GENERAL pinned one from Rockler. I have never compared but it seems to be accurate. I will tell you one thing though. The battery that came with it sure lasts a long time.

At Rockler

[Willyou]

Someone please correct me if I'm wrong. My understanding is that moisture meters work by sending a current through the wood and that more moisture carries current more easily. In other words, the current follows the path of least resistance. So, it doesn't matter that the wood is drier near the surface, the current will find its way to where there is wetter wood. Therefore, you are getting a reading of the wettest wood even though the pins (or pinless) are only touching near the surface, True??

[fredhargis]

It's probably not US-made. I have the GENERAL pinned one from Rockler. I have never compared but it seems to be accurate. I will tell you one thing though. The battery that came with it sure lasts a long time.

At Rockler

I have (had) that same General meter, and I was able to compare it to a "pro" model moisture meter...it was dead nuts in line with it. But this pro meter was one used by a clean up company after i got a leaky pipe in our finished basement....they used it to check the carpet and walls to see if they were dry. The General meter has a switch to change to building materials, so I checked with them. The only problem i had was that it died after about 2 years. BTW, I got mine when Lowes was clearing them out for $10...so I wasn't out anything when it gave up the ghost.

[jteneyck]

Someone please correct me if I'm wrong. My understanding is that moisture meters work by sending a current through the wood and that more moisture carries current more easily. In other words, the current follows the path of least resistance. So, it doesn't matter that the wood is drier near the surface, the current will find its way to where there is wetter wood. Therefore, you are getting a reading of the wettest wood even though the pins (or pinless) are only touching near the surface, True??

Nope, the current travels in a shallow arc between the pins.  If you cut a piece of wood that has a moisture gradient in it in two, and probe the ends at various depths to the center, you will see that the MC is lower at the surface and higher at the center. This is why some moisture meters have heavy duty pin probes that can be driven into the wood to various depths.  Delmhorst is one manufacturer that makes this type of meter. 

I'm not sure how pinless work, but they do indeed measure the moisture content at 1/4" and 3/4", if that is how they were designed.  Whether or not that's an average value, or some other value, I don't know, but the values reflect the gradient in the wood if there is one.  

You can easily verify all this by slicing a board that has a moisture gradient in it into say 1/4" slices.  Measure the moisture content of those slices with your pin meter.  Then dry those slices in an oven and measure their MC manually (the most accurate way to do it).  Compare the values.  I think you'll find the pin meter values are in pretty close agreement with the true values.    

John

[Willyou]

I understand what you are saying. But one thing I know for sure is that current will follow the path of least resistance. I think I can reason my way through what you say this way. Yes. If you slice through a piece with a moisture gradient, you will indeed get different readings; higher for the wetter piece and lower for the drier. However, if you use a short pin or pinless meter on a freshly cut chunk of wood you will of course, get a very high reading. When it is partially dry, a somewhat lower reading. And, when it is totally (by what ever standard you use) dry, the lowest reading. My understanding is that the current, seeking the path of least resistance, has an arc as you say, that goes as deep as it can to find that path. As the wood dries at lower levels the resistance gets higher and the meter readings get lower representing a proportion of some sort (maybe not an average) which represents the degree of gradient. I think that even when the meter readings reach what ever standard you choose to use for dryness, there is still a gradient as it will never be totally dry.

I'm not sure what your third paragraph shows except that there is a gradient. The long pin meters will, of course, get the pins closer to the path of least resistance and give you a better reading on the center of the wood, but assuming that a short pin or pinless meter is well designed to measure or interpret the gradient, it should work as well. I should have said in the last sentence of my question above that I think the short pin or pinless meters are interpreting the current through the gradient and giving a reading accordingly. I guess that is the challenge and the reason for cost differences.

This is what I've been told.

[jteneyck]

I understand what you are saying. But one thing I know for sure is that current will follow the path of least resistance. I think I can reason my way through what you say this way. Yes. If you slice through a piece with a moisture gradient, you will indeed get different readings; higher for the wetter piece and lower for the drier. However, if you use a short pin or pinless meter on a freshly cut chunk of wood you will of course, get a very high reading. When it is partially dry, a somewhat lower reading. And, when it is totally (by what ever standard you use) dry, the lowest reading. My understanding is that the current, seeking the path of least resistance, has an arc as you say, that goes as deep as it can to find that path. As the wood dries at lower levels the resistance gets higher and the meter readings get lower representing a proportion of some sort (maybe not an average) which represents the degree of gradient. I think that even when the meter readings reach what ever standard you choose to use for dryness, there is still a gradient as it will never be totally dry.

I'm not sure what your third paragraph shows except that there is a gradient. The long pin meters will, of course, get the pins closer to the path of least resistance and give you a better reading on the center of the wood, but assuming that a short pin or pinless meter is well designed to measure or interpret the gradient, it should work as well. I should have said in the last sentence of my question above that I think the short pin or pinless meters are interpreting the current through the gradient and giving a reading accordingly. I guess that is the challenge and the reason for cost differences.

This is what I've been told.

You might want to stop listening to those who told you that.  

John

[Willyou]

Hmm. So. Since you are unwilling/unable to give further clarification, I will assume you also don't know. Thanks for trying.

[titanxt]

Would electricity waste energy (amps?) in seeking 18% moisture at a slightly greater depth over the 14% moisture between the probes for less resistance? Moisture is present either way.

[jteneyck]

Hmm. So. Since you are unwilling/unable to give further clarification, I will assume you also don't know. Thanks for trying.

From Ligno (pin meters - electrical resistance):

[b]MD:  Fast and reliable measurements:[/b] After pins are pushed into wood, moisture percentages are indicated instantly. The integral pins can measure up to 7/16″ deep. For measuring thicker wood, make a fresh cut and measure the end grain. If this is not feasible, select one of the mini-Lignos MD/C or S/DC or DX/C with depth electrode E12. Select Package M-11 for measuring inside a dry kiln.

S/D:  The measuring depth of the mini-Ligno S/D is 7/16″. If you need to measure deeper to reach water damaged areas in the building envelope, choose the mini-Ligno S/DC with electrode E14 (up to 7″) or add the electrode E12 for depth measurements (up to 2″).

From Wagner (Pinless - radio waves);

Orion 920:  The Orion 920 Shallow Depth Pinless Wood Moisture Meter Kit features the Orion 920, carrying the Wagner tradition of superior accuracy forward with added capabilities and usefulness. The 920 takes moisture readings in your wood from the surface down to .25” (6.4mm) in depth. A flexible rubber boot makes the 920 durable enough to withstand your toughest jobs. While our Orion 920 meter offers exceptional performance and features, it’s important to note that it does not include a backlit screen, a feature available in our other models for added convenience in low-light conditions.

Orion 930:  The Orion 930 Dual Depth Pinless Wood Moisture Meter Kit features the Orion 930, carrying the Wagner tradition of superior accuracy forward with the added versatility of dual depth measurement in wood or other materials. The 930 takes moisture readings in your wood from the surface down to .25” (6.4mm) in depth in the shallow mode or from the surface down to .75” (19mm) in the deep scan mode. A flexible rubber boot makes the 930 durable enough to withstand your toughest jobs.

From Delmhorst:




John