Hardwood Floors December 2018/January 2019

AT THE SITE Manage Your Moisture Meter (Continued)

Take a stack of papers and measure the moisture content using the wrong setting. Add more papers or moisten some sheets until you get the same moisture content as out on the job. Then change the setting to the correct wood species setting and take a reading. The correct value is displayed. Now, you can determine the difference in moisture percentage between the correct setting and the wrong setting. Correct the other values by the same difference within the same moisture range. You can also call the manufacturer to ask how to correct the values. The worst case scenario is if moisture measurements have been taken and it has been forgotten to note the chosen wood species settings, and if applicable, wood temperature settings. Those measurements are useless, sorry. With the right moisture meter, following the manufacturer’s instructions, anyone can get reliable moisture measurements, which represent the moisture distribution of the wood floor at the time the moisture readings were obtained. Grete Heimerdinger is a Technical Specialist for Lignomat's moisture meter division. She can be reached at sales@lignomat.com.

It is very obvious that moisture meter measurements with any meter, pin or pinless, need to be corrected for the wood species measured. When documenting your readings of moisture measurements, it is crucial to always note the make of meter, the wood species settings, and where applicable, the wood temperature correction settings.

TWO FACTORS AFFECT THE MOISTURE VALUE INDICATED BY A PINLESS METER: 1. Differences between different boards of the same wood species. Pinless meters change the indicated moisture value based on the material inside the measuring field. Each piece of wood, even within the same species, differs in structure and density, which causes small variations between measurements within the same wood species at the same moisture level. These variations mostly stay within 1-2 percent if the moisture content is below the fiber saturation point at 25 percent. However, if the density within the same wood species varies too much, those limits will be exceeded. 2. Differences between different wood species. Corrections for different wood species are necessary because of density changes between different wood species. There is a large difference in density between a lightweight cedar board at specific gravity (SG) of 0.3 and a tropical hardwood with an SG of 1.1. To obtain accurate moisture percentages, the meter needs to be adjusted for different wood species. Many meters now offer built-in correction settings as an upgrade from printed correction tables. Wood species with the same density are put into the same wood groups. Most meters use the average density of the wood species as a code number. For instance, the wood group No. 45 is for wood species with a density of 0.45. The temperature of the wood does

Take photos and show where the photo was taken, so that the same spot can be found easily if rechecking becomes necessary.

For accurate record keeping, simply take a photo of the indicated moisture value and the chosen wood species (and temperature) settings. If possible, show the place where the photo was taken. If you ever have to go back for a claim, measure the same spot and compare measurements. What can be done if the meter has been set to the wrong wood species code number? It happens from time to time that an entire series of measurements is taken with a meter on the wrong wood species setting. Whether you’re using a pinless or a pin meter, the best solution would be to call the manufacturer and give the actual measured wood species, the moisture value, and the wrong setting number. They should be able to give you the corrections. If this was a pinless meter, you might be able to find the correction yourself.

not have a great impact on the indicated moisture values when using a pinless meter.

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