Review By Dean Bielanowski  Wagner Website -

Wagner MMC220 Digital Moisture Meter
By Dean Bielanowski

Ever built a project out of wood and found out later that nothing really stayed square, you found cracks or checks in the timber used or something badly warped not long after you completed it?

Perhaps you were using lumber that was too "wet", i.e. it had too much moisture inside. I'm sure we have all come across the problem at some stage in our woodworking hobby or career. And when you go down the path of trying to use reclaimed or salvaged wood, or even some you have chopped from your own back yard, how will you know when it is ready to be safely used?

To reduce the incidence of problems in selecting and using "wet" wood, you really do need a moisture meter. They range in price and features, some costing under $50, others up to a couple hundred of dollars.

Today we are taking a look at the Wagner MMC220. I decided to grab one for a look after hearing several good comments on this unit from fellow woodworkers.

The Wagner MMC220
Once you pull everything "out of the box", the first thing you will notice, apart from the fact that it ships in a nice and handy protective carry case, is that this moisture meter lacks the metal pins found on many cheaper moisture meter units. This is certainly not a bad thing! On the cheaper units, you have to actually bury the small pins into a part of the lumber you wish to test. This has the unfortunate consequence of leaving marks in the wood you are testing. The MMC220 leaves no marks on your lumber involving clean up later.
It's pin-less design also makes you more retailer-friendly when you can through the local lumber yard and scan wood for moisture content before purchase without leaving marks all over their stock!

In terms of size, the MMC220 measures 4 9/16" long, 2 3/4" wide and 1 1/16" high/deep. It fits comfortably in your hand and is light enough (at just .37 pounds to keep in your pocket) and to avoid any type of user fatigue. It utilizes a standard 9v battery to power the unit. A low battery indicator will appear on the large LCD display in the form of "LO BATT" when battery levels drop low. To help conserve battery power, the unit will automatically switch itself off if there has not been a significant change in reading values in the last 60 seconds.

The LCD screen is easy to read and the digits easy to decipher, even at more obscure viewing angles.

On the rear of the unit you will notice the scanning area plate. The MMC220 has a scanning area of 1 1/2" x 2 1/2". It uses electro-magnetic wave sensing technology for more accurate readings, as opposed to resistance determination as used by pin meters, which is subject to conditions that cause diminished accuracy. A maximum measuring depth of 3/4" is listed in the manual.

The MMC220 can supply accurate moisture readings between 5% and 30% moisture content. Ideally, you would be looking for a moisture content around 8% - 12% in wood before you would start building anything from it. This range is just the guide I personally go by. It may vary depending on who you talk to, or what you have read previously. I have had few problems using wood in this moisture range previously anyway. The unit is capable of measuring moisture content to a 0.1% accuracy.

Naturally, accuracy depends mostly, among other things, upon the user selecting the correct specific gravity (SG) setting on the unit for the species of material they wish to measure. The MMC220 is adjustable from 0.20 to 1.0 SG. This pretty much covers virtually all wood species used by woodworkers. The higher specific gravity ranges (past 0.80) can be used for exotic wood species. If you are not sure what the specific gravity of a particular species is, the unit ships with a small booklet containing many of the more commonly used wood species and their specific gravity values, allowing you to readily set the correct SG to take accurate moisture readings. The wood species listed in the accompanying species printed guide are somewhat localized to the United States in terms of common woods, however, this unit can be used anywhere for any species as long as you know the SG of the wood you are testing.

In terms of use, the unit is very simple to use. The On/Hold button will turn the unit on and off, by holding the button in for a few seconds. It also acts as a Hold button. This means you can freeze the current moisture reading on the screen. This is useful if you need to scan wood in a hard to reach place where you cannot see the reading. You simply lay the unit on top of the wood to test, allow it to gauge a reading and hit the Hold button once. This freezes the reading and you can then check the reading when you can again see the display.

The Species button allows you to adjust the specific gravity (density) setting of the unit so accurate readings can be taken on different timbers. You can press it once to bring up the current SG setting. Subsequent presses will increase the SG setting by 1 point at a time. Pushing and holding the Species button cycles the setting 10 points at a time for faster increase. Once the SG reading reaches 1.0 (displayed as 100 on the screen), it cycles back to the starting value of 0.20 SG (displayed as 20 on the screen).

Below the control buttons is a 10 place table where you can list your most commonly used species and their SG values for quick reference. Use a pencil or non-permanent marker to scribble these in so you can modify them later if needed.

To actually make a moisture reading, you simply turn the unit on, place it onto the wood to be scanned and press firmly down to engage the scanning plate onto as much wood surface as possible and allow the reading to stabilize. Ensure that if you are working with material less than 3/4" that the material isn't sitting on other material or else your reading may be inaccurate.

I tested the unit on a wide variety of species of lumber, each time adjusting the moisture meter for the species to be tested. As far as I could tell, accuracy was very good. I deliberately tested woods I new were still "wet" from being freshly or recently cut and the readings indicated a much higher moisture content that materials I knew had been kiln dried or air dried for much longer.

The MMC220 itself is very easy to use. In fact, I had mastered it without even needing to refer to the user manual. However, there is some useful information to know in the manual and the few pages it contains can be read entirely in a matter of minutes. The MMC220, overall, is quick and efficient to use. While I would have liked a feature to have been implemented that could scroll through your most used set of SG values for specific species (even 5 or so species), changing the SG (density) value was not overly troublesome or time consuming.

There is not a lot more to say about this unit. The features are simple (which is actually a good thing in this case) and there is very little to know to get it working correctly. My 6 year old daughter can use it properly with no issues! In terms of accuracy, the unit is factory calibrated. While I couldn't directly measure the accuracy, i was pretty sure it would be quite accurate given the type of tests I had done and knowing how well each piece of lumber I tried it on had been dried previously. I am confident in the units repeatable accuracy. It seems much more accurate than any pin moisture meter I have owned before.

Of course, this accuracy does come at a price. At around US$299.00 retail, the MMC220 moisture meter is an investment that requires a little budget consideration. But when it comes to measuring wood moisture, and avoiding costly problems associated with using wood that wasn't as dry as it should have been before use, I feel a little extra dollar investment in a good moisture meter is a worthy avenue to take for future piece of mind, and more solid and stable woodworking projects!

Wagner do have several other (less expensive models) in their range with similar features if you are looking for a cheaper alternative, but be sure to check features carefully to ensure the unit you buy will match your requirements.

Overall, however, I was very happy with the performance of the MMC220. If you have the money, it's a definite buy item.

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MMC220 Photos
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The MMC220's handy carry case provides added protection when not in use.

Small printed manuals provide all you need to know to use the meter.

The MMC220.

Large LCD display is very easy to read. Note also the printed table to allow you to insert information for commonly used species.

The MC220 uses one 9v battery.

Testing some radiata pine boards purchased from the hardware supply.

Altering the specific gravity setting for this board of Silky Oak.

10.5, this board is dry enough to use without too many problems.


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