Moisture Meters

Pin

Pinless

Moisture meters measure the percentage of moisture or water in wood. Woodworkers use them to determine whether or not the timber is too wet or too dry to be used for furniture making. If the timber is too dry, glue bond failure may occur and if too wet again you may face the same problem. Using a moisture meter irrespective of whether you’re a hobbyist or professional is essential.
I admit that up until recently I haven’t owned a moisture meter and have to a certain degree worked wood successfully without one, but I emphasise the phrase “to a certain degree”. Not every timber I worked was without its problems of cups, warps and bows. Not every timber I planed remained flat the next day. Had I used a moisture meter prior to working that wood I at least would have been informed of its moisture content (MC) and would have decided then and there whether or not this timber is workable. However, not always is the MC the culprit, as I mentioned in the kiln drying article on the blog. If the timber isn’t dried correctly, it can form stress and regardless of its moisture content you may face hard times working with it.

Pinned versus Pinless
A pinned style includes two pins that are proud on top of the meter. These two pins are inserted into the timber either face or, more commonly end grain to take a reading. A small electrical current is passed between the points, and the amount of resistance is correlated to a moisture content. Moisture is a good electrical conductor so the wetter the wood the less resistance there is to the current. The accuracy of a pinned version is affected by the variances in the naturally occurring chemical composition of wood species, but isn’t as affected by the difference in density from one species to another.
A pinless version penetrates deep into the wood using an electromagnetic wave through the area under the sensor pad. This creates an electromagnetic field which the meter correlates to a moisture content. The real beauty of a pinless version is it’s non-destructive, which means there are no holes bored into your timber and it scans a much larger area than the pinned version.
The debate regarding the accuracy of the two versions has been ongoing for years with only ever one outcome, pointing favourably towards the pinned version until recently. With technological advancements, the pinless style has been shown to be just as accurate with the added benefit of being non-destructive. However, it always boils down to the quality of the device and there are many manufacturers out there producing both versions that range in price from $30 to $1000.
All companies, regardless of version will make claims that their meter is the best in terms of accuracy. Knowledge through research will make you better informed as to the accuracy of their claims.
So how do we know which manufacturer to choose? Well lucky enough for you I have done this research over many months and am providing a link for you http://www.moisturemeter.com where you can see for yourselves which brand is better than others. These tests were conducted by experts and the methods they used are described on the website. I urge you to thoroughly go through all the brands tested so you can make a truly informed, unbiased decision. After all, money doesn’t grow on trees even though the leaves are the same colour.
After extensive research of many, many brands I have opted to go with a Wagner MMC 220.

With this meter, you also receive a clip-on carry case. Yes, this meter is fragile – you cannot exert more than 2-pounds pressure and a drop from 4 feet or more will result in damage to the unit, requiring that it be sent back for re calibration. I thought I’d point that out straight off the bat. Other than that, according to independent moisture meter experts it’s accurate and measures moisture in the wood and not on the surface of the wood. It measures softwoods and hardwoods including tropical species. In the manual you receive, there is a list of specific gravity for most commonly used timbers. If your timber isn’t listed they also provide a link where you can find this information.
In summary a moisture meter is a must have for any serious woodworker. If you’re building once or twice a year and you purchase timber from a trusted source then it would be a complete waste of your money to own one because, by the time you get around to building your project your wood would have significantly dried and acclimated to your shop’s environment.

On the other hand, if you’re buying timber from privateers and not so reputable businesses (and I could name a few) then it would make good sense to bring one with you. Not everybody’s honest and not everybody’s claim of their stock being dry is true. So, having a meter for your own peace of mind is money well spent in my books.

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