By Grete Heimerdinger, Lignomat
Oops … you made a mistake with the wood species setting while taking a lot of measurements. It happens, even though it should not. It could happen and now you are at home filling out the report for your last installation. Looking at photos and notes, you notice all moisture measurements were taken on the wrong wood species setting.
First, all moisture measurements pin and pinless need to be corrected for the wood species being measured, otherwise measurements are not accurate. It is very clear from the example below, that the species setting has a great influence on the moisture values indicated by a moisture meter. The same piece of wood measured with different settings will show 9.5% versus 12%.
All advanced moisture meters have built-in species corrections. The correct setting is provided by the meter manufacturers. Once the setting is chosen, the meter internally corrects all subsequent measurements and indicates the corrected value. Usually, the meter will keep that setting after the meter is turned off.
If you measure another species and do not change the wood setting, all measurements are corrected for the previous setting. You have some options so that you don’t have to go back and repeat the entire test series or determine the range of moisture, if you had the meter set to the correct wood species setting.
One option would be to call the moisture meter manufacturer and ask if they can tell, what the readings would have been, if the meter were set on the correct species setting.
Here is what you could do if you took measurements with a pinless meter. The following method for pinless meters only works if the wood species settings are based on the specific gravity (grou numbers go from 30-100 or from 0.3 to 1).
Pinless meter: Let’s assume, the non-invasive meter was set to Red Oak #60, and the meter should have been set to Hickory #74. On the “wrong” Red Oak setting the moisture percentages were between 11% – 13%. To find out what the range of moisture percentages would have been on the correct setting for Hickory #74, you can look for a sample piece of wood which measures between 11-13% on setting #60. Next, confirm the moisture range by taking a reading on #60.
The sample piece read on setting #60 12.0%. When changed to #74, the indicated value was 9.6%. Just a reminder, when taking moisture measurements, slight pressure needs to be put on the meter towards the surface. Do not just set the meter on the surface.
With this little experiment the correct range of moisture for the hickory was found. Second it was again confirmed that accurate measurements are only possible with correct wood species settings.
The sameprocedure can be used for pin meters. However, this conversion is only correct if the sample piece is from the same wood species at the same moisture range. In most cases, it is probably hard to find a piece of the same wood species at the same moisture level. Therefore, in the case of pin meter measurements, the true values can only be determined by calling the meter manufacturer and give the moisture range and the incorrect species settings those measurements were taken with.
Of course, it would be best to set the meter correctly to start with. However, mistakes happen and this is how you can eliminate going back and taking the entire measurement series again
First you find a sample piece which reads within the range you took the measurements. In our sample that would be 10%. Set the meter on 60 and note the moisture value.
Change the setting on the meter to #74 and take moisture measurements in the same spot on the sample piece. Some meters allow changes to the settings without even moving the meter.