Treatability problems—Relationships between anatomy, chemical composition and treatability

This report documents the results of phase 1 and 2 of a 3-phase research program. In phase 1, two hundred and fifty-six (256) Southern pine (pinus spp.) nominal 2 x 6’s (38 mm x 140 mm) from a single mill in Georgia (southeastern US) were evaluated for treatability with CCA preservative. After treatment, 128 pieces representing a broad range of treatment characteristics were selected and more fully evaluated for anatomical and chemical composition. No direct correlation was noted between CCA treatability and any of the anatomical characteristics evaluated in this study. Neither did a direct correlation between chemical composition and treatability seem to exist. The pit tori of all pits evaluated in this study were aspirated against the pit wall for this difficult to treat Southern pine lumber. This pit aspiration might have resulted from pre-treatment kiln drying. Later reductions in kiln temperature and increased kiln humidity (i.e., lowered wet-bulb depression temperature) reportedly resulted in improved treatability. In Phase 2, a methodology was developed to assess treatability after 3 treating schedules and then compare those results to permeability measurements and anatomical characteristics of matched material from 7 growth regions.