How Does a Moisture Meter Work?

Wagner Hand-Held Moisture Meters use an advanced electro-magnetic wave technology. This proven technology allows the user to quickly and accurately measure the moisture content of wood without the time consuming effort of driving pins into the wood. Wagner meters provide instant readings, scanning many board feet in seconds. Electromagnetic radio waves are sent into the wood without leaving any holes.

PIN METERS vs. ELECTRO-MAGNETIC WAVE - Why do they read different?

Pin-type moisture meters work on a resistance principle that basically measures the flow of electricity through a substance. This method is subject to many environmental variables that can dramatically affect moisture meter readings such as chemicals in the water trapped within the wood and the temperature of the wood. Most pin-type meter readings must be corrected for any difference in temperature above or below 70 degrees F.

Wagner Hand-Held Moisture Meters are virtually unaffected by surface moisture and temperature. (Except the 607 which is designed as a dual depth meter, capable of measuring surface moisture.)

Safe to Use - Wagner moisture meters produce less electromagnetic radiation than standard house wiring. In addition, Wagner meters have been tested and certified to comply with FCC and CE regulations.

PRECISION vs. ACCURACY

When referring to the digital readings of Wagner's MMC meters, often times a reference is made to precision. For example, the MMC210 is more precise than the MMC205. This is because the MMC205 only shows the MC in whole percentages with no decimal point. The MMC210 shows the MC in a tenth of a percent readings or ".1 precision." This does NOT mean that the MMC205 is less accurate. This is simply referring to how the MC is displayed.

Meter precision does not equate to accuracy.

ACCURACY

ASTM 4442-92 Oven Dry - this is the standard to which all wood moisture meters are compared for accuracy. The Wagner Moisture Meter is as accurate, or more accurate than any moisture meter that is on the market. This can be verified by several university meter studies which are available upon request.

Studies which may refer to another model, relate to all of our wood moisture meters because they have the same circuitry, technology, and accuracy. The L609 and C575 meters are the only exception because of different technology used.

WAGNER MOISTURE METER USAGE TIPS

Be sure to press down firmly on the center of the moisture meter with approximately 3 pounds of pressure to ensure good sensor plate contact with the wood surface. This is especially important on rough-sawn lumber. Do not take readings with the meter where there is a noticeable defect or knot in the lumber.

If there is visible surface moisture or water, wipe off any excess, and let the surface of the wood dry-out for a couple of minutes. Next, use the moisture meter to take the reading. If possible, turn the board over and use the meter to measure the other side. If the thickness of the piece is greater than 1 1/2 inches (1 inch with model L607and L609), it is a good idea to use the meter to take measurements on both sides.

Ensure that there is nothing (especially your hand or metal) under the material you are measuring. In order to take a valid measurement, the meter's sensing area must be completely covered with the wood you are measuring. If the meter's sensing area is not completely covered, your moisture content reading may be lower.

WOOD TEMPERATURE OR SURFACE MOISTURE

Wagner moisture meters are virtually unaffected by surface moisture or temperature. The exception is Wagner's L607 meter, which was designed to measure surface moisture to test the cure of waterborne finishes. Most competitors' meters are affected by surface moisture and temperature.

Standing water or visible water on the board can affect the reading. Visible water should be wiped off.

NOTE: If water is allowed to soak into the wood, it will naturally show higher moisture content. If a piece of wood is quite rough, it will soak up the water quite readily, affecting the readings for all moisture meters.

RUGGEDNESS

Wagner's hand held moisture meters are designed for compact convenience. They are not easily damaged, but Wagner meters can be damaged by being dropped or slammed down on hard surfaces, as can any moisture meter. For large volumes of wood, an inline moisture measurement system should be used.

VERIFYING CALIBRATION

Wagner moisture meters are calibrated at the factory. With proper care the meters stay in calibration. In the event that the moisture meter has been dropped or you suspect for any reason that the meter is out of calibration, a calibration verification block is available. Anytime that the meter is not reading correctly on the calibration block, it should be sent to the factory for calibration.

SENSING AREA

Narrowest Measurement 1 ½" for C575 1 ½" for L606 and L607DD 7/8" for L609 1 ½" for MMC 205, 210, 220 1 ½" for MMI 1100

Depth of Measurement ¾" for MMC200 series, MMI 1100, C575, and L606 ½" for L607, L609

CORRECT MOISTURE CONTENT (MC)

The correct moisture content varies from region to region and indoor or outdoor use. Refer to local builders or associations for appropriate range in your area. If the wood is to be glued and is too dry, it won't bond; if too wet, it won't hold.

Resources for determining the proper moisture content:

• University Forestry Departments
  
• Industry Associations

Forest Products Research Laboratory in Madison, WI, 608-231-9200

FROZEN WOOD

On frozen wood with up to 15% MC, accurate measurements can be obtained. For frozen wood with more than 15% MC, contact technical support for help.

Wet pockets and gradients continually equalize as moisture passes from fiber to fiber and to surrounding humidity levels.

Moisture meters measure the average of the area scanned. Meters can be held in one place or slid along the length of the wood. Most Wagner moisture meters are unaffected by the grain of the wood, except the L609 meter which must be placed parallel to the grain of the wood.

SPECIFIC GRAVITY REFERENCES

First refer to the handbook that comes with the moisture meter or the CD that was included with meters purchased after January 15, 2004. If unable to find the SG in those documents, go to Wagner's Specific Gravity Resources page.

Measuring Non-solid Wood

Wagner has developed meter correction factors for the following non-solid woods. It is available from technical services. This gives a relative reading because of the glues and resins.

• Plywood - SYP, CDX, Douglas Fir
• OSB "“ SYP, CDX, Douglas Fir

Definitions
Engineered - has layers of wood like plywood
Laminate - has very fine fibers or dust particles which are held together by glues and resins with a picture on top

Large Lumber and Wood Products Manufacturers Meters

WOOD TREATMENT NOTES

CCA (1% CCA, 99% water)

• Copper - Basis for killing insects
• Chromium - Helps copper travel & permeate wood cells
• Arsenic - Gels copper into wood so it will not leach out

ACQ Environmentally safer than CCA

• Copper- Basis for killing insects
• Ammonical - Ammonia/salt based - Helps copper travel and permeate wood cells
• Quantenary - Gels copper into wood so it will not leach out

Both CCA & ACQ will cause readings on meter to be higher.

The process for treating wood is: Soak wood in pressure chambers and then use vacuum to pull out excess fluid. MC is 30 - 40% after treatment. The wood is then put on drip pads for 2 - 3 days and then kiln dried to their MC specification.

OVEN DRY TEST MUST BE DONE ON ANY TREATED WOOD.

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