Grade Stamp Moisture Designations – What they may or may not mean for treatability (Part 1) Moisture content plays a crucial role in the treatability of softwood lumber products with waterborne preservatives. Wood that is properly conditioned or dried to a moisture content below the Fiber Saturation Point (28-32% in SYP) will generally accept treatment as the preservative under pressure can be forced into the wood cells in those areas left voided by water. When lumber is processed at the sawmill, it is sorted by size and length and stacked on sticks to allow for air movement between the layers in preparation for drying, whether air drying or kiln drying. Air drying is a very effective and consistent conditioning practice but requires time and occupies a lot of area. Kiln drying, while more costly on an energy basis, can be accomplished in as little as 24 hours. Accordingly, a large majority of the softwood lumber being treated in our market today is kiln dried. After the lumber is out of the dry kiln and allowed to cool, the lumber can then be broken down at the planer mill where it is dressed to a standard size, graded, trimmed to the proper length and grade stamped prior to being sorted and packaged. #GradeStamps #MoistureDesignations #Sawmill #KilnDrying
