Differences Between Pin vs Pinless Moisture Meters
When looking for accurate wood moisture meters, you’ll immediately run into two different styles: pin vs pinless moisture meter. Which is the better addition to your tool belt? There are some basic differences that you should understand before you buy.
1. How Moisture Meters Work
How pinless moisture meters work
Pinless moisture meters work via an electromagnetic sensor pad that comes into contact with the wood surface but does not physically break or damage the surface to take a reading. Pinless moisture meters can measure moisture content from the surface down to .25″ or, for deep measurements, from .75″ to 1.5″.
How pin moisture meters work
Pin-type moisture meters have two metal probes that must physically penetrate the wood’s surface in order to take a moisture reading. When the meter is turned on, an electrical current flows from pin to pin and measures the resistance.
Pin-type meters take advantage of the fact that water (with salts and impurities) conducts electricity and wood doesn’t. This makes it possible to determine the moisture content of wood via measuring the resistance to an electrical current. Drier wood will show more electrical resistance.
Broken or bent pins are one drawback of a pin type meter. This is because the pressure used to push the probes into the wood can cause them to bend or break. (Some woods are harder than others and with dense wood, it can be difficult to insert the pins. Broken and bent pins are more common with harder species of wood.)
Of course, if the pins on your moisture meter break or bend, they’ll need to be replaced. This is not only inconvenient but, if your pins break on a regular basis, it can be expensive as well.
2. Electromagnetic Sensor Pad vs. Pins
The difference between a pin and a pinless moisture meter rests in the underlying technology.
Pin meters measure the resistance to an electrical current flowing between the two pin tips. Pin meter accuracy is affected by the chemical composition of wood, which varies from species to species.
Whatever type of wood moisture meter you’re using — pin or pinless — you’ll need to take multiple readings to get an overview of the wood’s moisture content. However, this is much harder to do when you’re using a pin meter because pin meters only measure the moisture content between the two pins and nowhere else.
In other words, you’ll need to take far more measurements to approximate what a pinless meter can easily do in one quick scan. Remember, each reading with a pin meter requires poking two new holes in the wood.
In contrast, pinless moisture meters use a large sensor pad and emit electromagnetic signals to measure the moisture content of the wood. This allows you to quickly and accurately scan large areas and get instant moisture meter readings. Pinless meters allow you to scan many board feet in just seconds without the time-consuming effort of driving pins into the wood.
3. Holes vs. No Holes
As we’ve already mentioned, a pin meter needs to penetrate the wood’s surface to measure the moisture content. Therefore, each moisture content reading will make a pair of pinholes in the wood, and as we noted above, you’ll need more than one reading to get an overall view of the wood’s moisture content. For 2x4s or firewood, this probably won’t be a problem.
However, if you’re measuring the moisture content of expensive wood flooring, furniture, cabinets, or other fine woodworking projects, these pinholes will become a series of blemishes on the wood’s surface. In contrast, pinless meters with their flat, smooth sensor pad don’t cause any damage to the wood.
4. Fixed-Depth Readings vs. Variable-Depth Readings
Pinless moisture meters generally operate at two standard reading depths: ¼” below the wood surface, and 3⁄4” below the surface. For most woodworking projects, like wood flooring or cabinets, or for building materials, these depths provide the necessary moisture content readings.
When using a pinless moisture meter you’ll need to be careful about how much pressure you apply. If you apply too little pressure there might be a slight gap under the device that will affect the accuracy of the reading. In fact, just the position of your hand can affect the accuracy of some less expensive moisture meters.
With pin moisture meters the moisture content reading is taken at the depth of the pins. That means if the pins aren’t inserted properly, the reading may not be accurate.
As we mentioned above, the pins on pin moisture meters can, at times, be difficult to push into the wood. While this isn’t usually a problem with softer woods, it can become a real issue with hardwood species. This is often how pins end up bent or broken. (Longer pins are more likely to break during use.) When this happens, if you don’t have replacement pins on hand, you’re out of luck. Your meter is unusable.
All moisture meters for wood need to be properly calibrated in order to provide accurate moisture measurements. High-quality pin and pinless meters allow you to verify factory calibration using a calibration reference device. If you find that your meter is out of calibration, you send it back to the manufacturer for recalibration.
Our Orion line of moisture meters goes a huge step further by providing you with an On-Demand Calibrator device that allows you to actually recalibrate your own meter. In other words, you don’t need to send your meter back to us for recalibration.
The accuracy of both pin and pinless moisture meters depends on using them correctly according to the manufacturer’s instructions. It’s also a good idea to ensure a low battery isn’t causing inaccurate readings. Our meters include a low battery indicator.
6. Moisture Meter Settings
In order to correctly use any meter, either pin or pinless, you’ll need a wood species adjustment table or, for programmable meters, the ability to enter the correct species setting.
Pin wood moisture meters are sensitive to temperature and, because of this, all quality pin meters will come with a temperature correction chart.
Pin meters are also sensitive to a wood’s chemical makeup which differs according to species. Therefore, quality pin meters will always ask you what type of wood you’re measuring.
Pinless moisture meters are sensitive to a wood’s specific gravity (i.e., density). Because this varies according to species, you’ll need to set the meter to the proper density setting before you take a measurement.
Pinless wood moisture meters are faster because they can scan many points in a quick swipe. If you used a pin meter, you would need to take several readings to cover the same size area. This is because a pin meter only measures the moisture between the two pins. Remember, each time you take a reading using a pin meter you leave behind two small pinholes in the wood.
Are Moisture Meters Affected by Surface Moisture?
Pin meters that use 1 1/4” length or longer pins with insulated shafts aren’t generally affected by surface moisture on the wood. Pin meters using only short pins without insulated shafts are far more prone to problems with surface moisture.
Surface moisture can also be a problem for pinless meters. For example, when the wood has a small amount of condensation on it, a pinless meter might detect a moisture measurement range from 10-20% higher.
Our IntelliSense™ technology greatly reduces this problem. IntelliSense allows our moisture meters to minimize the effect of slight amounts of moisture on the surface of the wood. In other words, our meters read the moisture in the wood, not on the wood as other moisture meters do.
Using Relative Measurement Mode
Relative measurement mode is used for obtaining relative, rather than absolute, measurements. It’s typically used for non-solid wood applications such as drywall. You might use a moisture meter to get an idea about how wet or dry a piece of drywall is, for example.
With relative measurement mode, the meter doesn’t tell you the actual percentage of moisture content in the wood, but rather provides relative measurements of a non-solid wood building material by measuring a known dry area of the material to establish a baseline, and then further scanning the material to determine if there are areas of the material that measure significantly higher than the dry baseline measurement. For example, this is useful when you’re trying to find a water leak. Locating wet spots can greatly help in determining where a building may have a leak.
Make sure you know what features to look for in a moisture meter.
Free Download – Is a Pin or Pinless Moisture Meter Best For You?
For more information about Wagner pinless wood moisture meters see our handy Orion® Moisture Meter Comparison Matrix.
Tony Morgan is a senior technician for Wagner Meters, where he serves on a team for product testing, development, and also customer service and training for moisture measurement products. Along with 19 years field experience for a number of electronics companies, Tony holds a B.A. in Management and his AAS in Electronics Technology.
Last updated on November 28th, 2022