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How to Use a Pinless Wood Moisture Meter

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Blog entry by WoodGoddess posted 622 days ago 2926 reads 3 times favorited 2 comments Add to Favorites Watch

I’ve discovered throughout the Internet that often times customers are a bit confused or disheartened when selecting a moisture meter and even more so when it comes time to use it. So I’ve gather a bit of “quick tips” that I hope will help users faced with a pinless moisture meter.

What is a pinless moisture meter and why use it?

A pinless wood moisture meter is a reliable, non-invasive way to assess moisture content (MC) to ensure stable, lasting wood strength and performance. Pinless moisture meters for wood, also called “non-damaging” or “non-destructive” moisture meters, send electromagnetic wave signals below the wood surface in order to read the wood’s MC. Pinless moisture meters for wood operate on the principle that the most accurate MC reading lies below the wood‘s top surface, where moisture and ambient RH may skew the MC reading.

Wood moisture meter technology continues to drive towards ever-increasing accuracy and efficiency. A pinless moisture meter represents the best possible option for non-damaging, quick, simple, and accurate moisture measurements in wood without the time consuming effort of driving pins into the wood.

When is a pinless moisture meter typically used?

Hobbyists, builders and consumers use wood moisture meter products to measure, assess and manage the moisture content (MC) of their wood in woodworking projects, home-building projects and during the installation of hardwood flooring (to name a few).

What is wood moisture content?

When wood is processed into lumber, it is kiln dried. Even so, moisture (measured as the wood’s moisture content, or MC), remains in the structure of every wood cell even after the drying process. In fact, moisture is a crucial element in the strength and durability of wood throughout its lifetime.

In the lumber processing phase, optimally the wood should be dried to a target MC that enables the wood to be in balance with the relative humidity (RH) and temperature of its intended end product environment (usually between 7-12% for indoor applications). Wood continually loses or gains moisture until the amount it contains is in balance with that in its surrounding environment. This moisture balance is known as the wood’s equilibrium moisture content (EMC), and it means the wood is good to go.

However, wood’s MC levels do fluctuate with changes in the surrounding RH of the air. When RH is high, wood absorbs moisture and expands from it; when the RH goes down, wood shrinks as it releases moisture into the air. Shrinkage and expansion in wood products are normal to a degree, but using a wood moisture meter can provide information about how the changes in the wood’s MC affect the end product’s structural stability.

Extreme moisture conditions can lead to problems with excessive cracks between boards, crowning, cupping, or buckling in wood flooring applications. In woodworking applications, extreme moisture conditions can lead to glue-line failures, cracked or checked finishes, fuzzy grain after machining, gluing, laminating and veneering failure, sunken joints or uneven surfaces in panel manufacturing and panel end splits.

How do I use a pinless moisture meter?

To use a pinless moisture meter, simply turn it on and place it on the wood surface. If the wood moisture meter has a programmable setting for the species of wood you are using, be sure to select the appropriate wood species setting first. Otherwise, it will be necessary to use a species adjustment table, usually provided with the moisture meter by the manufacturer, if the meter is not programmable for various wood species. The meter will display a MC reading in either analog, LED, or digital format, depending on the model used.

Here’s a bit of side information and things to consider when looking into a pinless moisture meter.

Pros

Pinless meters measure the MC inside the wood usually to a depth of ¾”, not just at the wood surface.

Users can quickly scan the wood for its MC by running a pinless wood moisture meter along the woods surface. Users can measure the board’s full width and length, and then can turn the board over to get the thickness MC readings.

Internal MC measurement and full board measurement capabilities lead to more precise MC board profiles when using pinless moisture meters for wood. Time savings are also a big advantage when compared to pin meters.

Unlike pin-type meters, pinless meters do not require corrections for temperatures above or below 70 degrees. Also, it does not matter which way you set a pinless moisture meter on the wood, as pinless meters are unaffected by the orientation of the grain. Pin-type meters usually are required to be placed parallel to the grain to get accurate MC measurements.

Pinless moisture meters for wood leave no marks and do not damage the wood when measuring, which is crucial to furniture, wood flooring and/or woodworking projects.

Pinless meters do not use any pins, which can break over time and with wear. No spare parts are required when using pinless meters.

Pinless meters generally reach better into obstructed spaces (under a counter or behind a fixture), where pin meters cannot be properly inserted and can be difficult to use.

Dual-depth pinless moisture meters for wood allow users to measure the MC at two specific depth levels.

Cons

Pinless moisture meters, like any moisture meter, can fall out of calibration, which can lead to inaccurate MC testing results. However, pinless meters are easily re-calibrated by sending them into the manufacturer; some manufacturers provide a calibration verification tool for quick spot checks in the field.

Pinless meters cannot measure the MC of the wood at a specified moisture gradient depth for shell and core MC measurements.

On thin lumber applications, the electromagnetic wave signals of pinless meters can be influenced by the substrate directly under the thin piece of lumber. Review the depth penetration specifications of the manufacturer prior to using the meter.

In rough lumber applications, a pinless wood moisture meter can read a slightly drier MC reading due to the air gap caused by the little fibers in rough lumber. Usually, this should only have a very small effect, if any, but exceptionally rough lumber may necessitate adding 1-2% to get an accurate MC reading. It’s important to use some pressure and force the meter down firmly against the wood on these types of applications.

The sensing plate scanning areas of pinless moisture meters must always be covered by the wood material, as these scan areas are usually 1.5” W X 2.5” L. The dimensional shape of the product might be a limiting factor in using these types of meters, so check with the manufacturer about the sensor plate scan dimensions.



2 comments so far

View JohnnyStrawberry's profile

JohnnyStrawberry

241 posts in 951 days


#1 posted 622 days ago

Nice comprehensive writing as usual! ;)
Thanks for sharing.

-- What are those few hours of mine compared to those decades Mother Nature has put in it!

View reddyfox's profile

reddyfox

2 posts in 386 days


#2 posted 386 days ago

The article is really cool! I work with Microwave Moisture Sensor due to my job and I must say you are absolutely right at any point. thanks for sharinf the article.

-- Microwave Moisture Sensor

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