Tree conversion involves cutting down trees in winter and transporting logs to sawmills to be cut into boards. There are three main conversion methods: through and through sawing cuts logs parallel to the grain but can cause cupping; tangential sawing cuts at 90 degree angles to produce flame figured boards but are prone to shrinkage; quarter sawing cuts at 45 degree angles to produce stable boards with attractive grain for flooring but is the most expensive due to extra processing steps.