State:

a) Two methods of testing for moisture content.

b) Two advantages of seasoning timber.

Determination of Moisture Content

The quick and easy way to determine the moisture content of timber is by use of a moisture meter (video here). is works by pushing two electrodes into the surface of the timber and passing an electric current between them, the quicker the current the more moisture in the timber the higher the reading. But all is not so simple, if the moisture meter doesn't take account of the differing densities of the timber then two completely different timbers with different densities and different moisture contents could give the same reading.

A more scientific method, used by timber importers and suppliers, who are seasoning timber, (although admittedly not used on the building site), is the determination of the moisture content by weight.

A sample of the timber is taken usually about 12mm along the grain. This sample should not be taken from the end of a plank, but at least 1 metre in, to ensure a representative sample.

This sample is weighed as soon as it is cut, and the weight noted, is called the Wet Weight.

The sample is then placed in an oven, to dry all the moisture out, when dry the sample is weighed again and this noted weight called the Dry Weight. The operator knows when the sample is dry, when he weighs the sample and the weight is constant.

Using the two weights:

Wet Weight - Dry Weight X 100 = Moisture Content (%)

(over) Dry Weight

Seasoned Timber

Timber that is well seasoned is lighter and more stable, this means it is less likely to shrink warp and split in use.