What is the purpose of a preservative retention test?

The purpose of a preservative retention test is to determine the amount of preservative that has been absorbed by the wood. This test is crucial in wood preservation because it helps assess whether the wood has received an adequate amount of preservative treatment to protect against decay, insects, and other wood damaging factors.

By measuring the retention levels of the preservative, wood treatment facilities can ensure that the application meets the necessary standards for effectiveness. The results of this test inform whether the treatment process needs to be adjusted to improve preservative uptake and improve the wood's longevity.

Other options focus on different aspects of wood properties, such as water absorption or decay resistance, which do not directly relate to the purpose of assessing preservative retention. Staining is also unrelated to preservative retention, as it concerns aesthetic properties rather than protective treatments. Therefore, option C accurately captures the central role of preservative retention tests in wood preservation practices.