Why only Clear Heart Redwood or Western Red Cedar?
There are stringent requirements for the grade and type of wood that should be used to make a wooden tub, although these are not always adhered to by other manufacturers of wooden tubs . The wood must be naturally decay resistant and must swell enough to provide a good seal, but it must not swell so much that buckling occurs. No knots or sapwood (the lighter colored wood from the outer part of the tree) can be used, since the knots can leak and the sapwood will decay like any other white wood. Only the heartwood from the center of the tree possesses natural decay resistant properties. The wood to be used in a wooden hot tub must also have a pleasant appearance. Despite the high cost and limited availability, Redwood fulfills all these requirements better than most any other wood, providing the grade is clear and all-heart (teak, jarrah and a variety of cedar are also excellent woods for hot tubs).
