A.) A phenomenon occurring in wood when wood tries to expand, due to moisture gain, but cannot because of some restraining force. When the same wood loses the moisture, it will shrink the same amount as a similar piece of wood. This phenomenon is why cracks in wood floors continue to widen with repeated mopping when the cracks are filled with dirt and cannot expand with moisture gain. b.) Caused when wood strips or parquet slats absorb excess moisture and expand so much that the cells along the edges of adjoining pieces in the floor are crushed. This causes them to lose resiliency and create cracks when the floor returns to its normal moisture content.