timber appraisal the residual amount after all costs of production other than stumpage have been subtracted from the sale value of the product —note 1. conversion surplus for saw timber is the lumber sale value; that for pulpwood is the sale value of bolts delivered at the mill —note 2. the conversion surplus may be divided into two parts (not necessarily equal), an allowance for profit-and-risk and stumpage return This definition last updated 07/28/2008