Stain Control in Eastern White Pine – Using Ammoniacal Zinc Oxide in Mill Conditions

Sixty thousand board-feet (Mbf) of green, rough-sawn 1-inch eastern white pine boards (Pinus strobus) were treated with an ammoniacal zinc oxide solution under mill conditions to examine its effectiveness in the control of stain appearing in the process of kiln-drying or air-seasoning the lumber during the summer months. Ammoniacal zinc oxide controlled brown stain in all but 8 percent of those boards observed, while boards treated with standard sodium fluoride showed stain in 20 percent. Ammonia smell, while noticeable, was not considered unbearable. Air-seasoned treated lumber also remained unstained and mill personnel stated that the treatment compared favorably with their standard sodium penta-chlorophenate treatment. A supplementary investigation of air-seasoning performed with 3 Mbf of green rough-sawn I-inch eastern white pine established that zinc was the active ingredient preventing fungal staining and that altering the distribution of zinc in the wood altered its effectiveness during initial air-seasoning and any subsequent wetting of the wood. Zinc solutions compared favorably with sodium penta-chlorophenate in controlling fungal stain. Ammoniacal solutions without zinc were ineffective. All treatments deteriorated at approximately equal rates when the boards were continually re-wetted. The zinc salt was more effective when distributed throughout the outer 3/16-inch layer than when concentrated in the surface 1/16-inch layer.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member