Common Moisture Meter Mistakes
When to Use a Moisture Meter
When trying to diagnose or prevent moisture problems in wood flooring and other wood projects, the obvious tool to use is a wood moisture meter, and it follows that the first obvious mistake is not to use one. But there are several factors to consider when both choosing the right meter and using the meter you’ve chosen. Your choices can mean the difference between accurate moisture content (MC) reading and a potential problem down the road.
There are two basic types of wood moisture meters: pin-style and pinless. Read more about the top differences between a pin-style vs pinless meter.
Pin-style meters use two narrow metal probes inserted into the wood product you are testing. An electrical signal is passed between the tips of the two probes, and the resistance measurement is then interpreted into a moisture level content read on the meter. Large hammer probes can be attached to a hand meter for deeper measurements as the probes are driven in by force, or shorter pins are most commonly pushed in by hand.
As suggested by this common name, a pinless meter does not use pins or probes. Instead, it uses radio or electromagnetic signals that will change characteristics depending on the moisture level in the wood being tested.
So, while the meter types are fairly easy to understand, several mistakes still prevent these tools from being an asset on the job site. Some are problems that are inherent to certain meter types, but others can be easily avoided with little knowledge. What should you watch for?
Common Moisture Meter Mistakes
- For a pin-less type of meter, not knowing the meter’s reading depth. For example, if the meter you’ve chosen takes readings up to 1 ½” deep, but you’re taking readings on already-installed ¾” thick flooring, the reading you get will be somewhat affected by the MC of the subfloor. Not necessarily a helpful set of moisture readings from which to make decisions.
- Using too little pressure. Pinless meters can produce improper readings if the correct pressure is not applied. Too little, and the air gap under the meter’s sensor can impact the reading it takes. Some lower-end meters are even skewed by the position of the user’s hand and can vary depending on the hand’s position. It is unnecessary to apply more than about three pounds of pressure for most pinless meters.
- The obvious risk of over-stressing a pin-style meter is that pins can bend or break. Most pin-style meter manufacturers are clear that pounding or banging on the meter is not the correct way to insert the pins into a pin-style meter. Hammer probes are built to withstand more force, but over time, even these more rugged pins can break, especially in hardwood applications.
- Improperly driven pins. Pin-style meters (and even the hammer probe type) take considerable pressure to reach the proper pin depth. In softer woods, the effort exerted is often minimal. Still, when working with many hardwoods, especially some very dense tropical species, the effort needed to insert the pins to depth properly can become quite a challenge – if not virtually impossible – particularly if your meter is not constructed to take that type of force. Bent or broken pins or even cracked meter housings become more common with increased wood types density. The temptation is not completely to insert the pins, but obviously, the reading will not be taken at the correct depth. A reading taken with pins close to the surface will never accurately reflect the moisture conditions deeper in the wood.
- Trying to take a shortcut. Because of the effort to insert pin-style meters or their tendency to bend or break, it can be tempting to shortcut the testing process. This will speed up the testing, but it will not give any sense of the real moisture conditions of the wood or wood flooring that will be used. When testing large quantities of wood, or multiple parcels, it can be tempting to only test a few representative boards from the edges of the bundle. But even in acclimated wood, moisture conditions can change in areas with more restricted airflow. Handheld moisture meters, like the Orion® 930, let you “scan” lumber or wood stock to quickly gauge the moisture conditions in much of the wood. But if a representative number of boards aren’t tested, the potential for trouble will still be high.
- Overlooking general maintenance. Any meter will suffer when exposed to high temperatures, overly wet conditions, being dropped, or other circumstances compromise the integrity of the housing and the circuitry. But even something as seemingly minor as peeling insulation on the insulated pins of hammer-style probes can skew the meter readings. Because the signal is not restricted to a certain depth of the wood (at the tips of the probes), readings will not be precise depthwise and may represent a sort of composite reading of the signal along the length of the probe or simply read too shallow based on where the signal is strongest.
Pinless meters may also give skewed readings if their sensors become scratched or damaged. Lack of regular maintenance can also upset the calibration of the meter. Only the Wagner Meters Orion line of moisture meters provide an On-Demand-Calibrator to recalibrate the meter almost instantly.
- Not using the correct species settings or species adjustment. Most moisture meters use either user-programmed species settings or species adjustment tables. A piece of oak will have different properties than Douglas fir, so different species settings would be needed for these two. But if your meter doesn’t allow for those differences, the readings it takes will mean poor decisions about applied finishes or its readiness to be installed. Be sure you’ve read and understood the settings for your meter.
Free Download – Is a Pin or Pinless Moisture Meter Best For You?
Can a Moisture Meter Be Wrong?
A moisture meter can be an invaluable tool for advising finish and adhesive options or for avoiding moisture-related problems in a finished project. But if improperly used, a moisture meter will not do the job it is designed to do. Know your meter, follow the manufacturer’s instructions and be sure you are choosing the meter that best suits your purposes. Then you’ll easily avoid those costly mistakes.
As Sales Manager for Wagner Meters, Ron has more than 35 years of experience with instrumentation and measurement systems in different industries. In previous positions, he has served as Regional Sales Manager, Product and Projects Manager, and Sales Manager for manufacturers involved in measurement instrumentation.
Last updated on June 14th, 2022