EFFECT OF STEAMING ON TREATABILITY OF DOUGLAS-FIR HEARTWOOD WITH SODIUM OCTABORATE TETRAHYDRATE

The use of presteaming to enhance boron treatment of Douglas-fir heart wood lumber was evaluated using specimens cut from unseasoned and air- dried boards. For both types of specimens, an hour of presteaming with in an hour of boron treatment produced the most marked improvement in boron retention. Presteaming within an hour of treatment also improved boron penetration when measured after a 30-day diffusion period. A lo nger (3-hr.) presteaming period enhanced neither immediate uptake nor penetration after 30 days of diffusion.