The Can You Trust Them article cites somewhat contradictory findings:
“Frozen water. We ran two different tests to determine whether the meters could detect frozen water. In the first, we compared a sample of .135″ laminate and wet paper frozen. No meter gave a reading differing from laminate alone. This suggested that the meters do not detect frozen water.
In the second set of tests, we took four panels in various stages of wetness and deterioration: moist, saturated, advanced brown rot and white rot. Reading were taken wet. Then the panels were frozen and tested again. Comparing the wet and frozen readings, most of the frozen readings were lower than the wet, but not all. We cannot account for those few frozen readings that were the same as room temperature readings or higher.
While the tests werent the same, the discrepancies leave questions. Still, the bottom line is not to trust any moisture meter readings taken when the laminate is below 32F. Wait until the temperature warms and the laminate has thawed.
As a side note, glycol, a byproduct of the resins used in boats and the cause of some blistering, will not freeze and can be detected in sub-freezing weather.”
Moisture meters are used in lumber yards that are not heated. I found this quote to be interesting:
Once the wood is under 30% MC, a moisture meter starts to work and works down to 6% MC or so. At this moisture, the only water in wood is called bound water and is not a liquid. So, it cannot freeze. So, you can use a meter on wood that is under 32 F and achieve good readings.
So, if the water in the balsa core is bound water, the moisture meter (maybe with an adjustment) should work?