"Short Wave Sportfishing" wrote in message
...

It depends on your definition of density. Using a standard definition
of density like the mass per unit volume of a substance under
specified conditions of pressure and temperature, then no, a moisture
can't measure density in that sense.

You measure density by specific gravity - that is weighing the
material in question or determining it's relative hardness (density)
by deforming the surface or the shape of the material in some manner
and measuring the force needed to do so. Then applying some
mathematics, you have density.

As I understand it, and have demonstrated to myself by playing with
the one I have, moisture meters measure resistance. They do this by
using a 1 KHz modulated signal anywhere from 5 to 40 KHz in frequency
across a predetermined distance (centers of the probes or pads).

The presence of water would necessarily mean that there was lower
resistance, but it doesn't mean that the material is less dense.
We're not dealing with a solid block of something - this is woven and
porous fiber. The density of the fiberglass and resins isn't the
issue - it's the water in, through and surrounding the fibers and it's
penetration through the resins.

Think of it this way. If you fill a ceramic bowl with water and put
the meter pads in it, what are you measuring? The amount of water in
the bowl or the density of the bowl?

Yes/No?

Later,

Tom

Whatever floats your boat. Actually, I was trying to recall what limited
knowledge I have with ultrasonic nondestructive testing and how it may (or
may not) apply in the moisture testing. Ultrasonics are used to test for
flaws or inclusions in welds, but can also be used for other materials to
measure thickness and changes in the density of the material. My bag was
thin films for optics and we but used many of the same laws (Snell's law and
others) although we delt with the refractive index of a material rather than
it's density. I donno ... just a thought.

Eisboch