Over the past five years a number of factors have come together to revive interest in treatment of Canadian softwoods with borates. These include opportunities in overseas markets where termites are a problem and the recognition of borate-treated framing as an environmentally acceptable alternative to soil poisoning and house fumigation. Pressure treatment followed by a short diffusion period is now the favoured approach since it is much faster than the old dip-diffusion methods. If Alberta sawmills are to take advantage of this new market opportunity they must be able to effectively treat spruce-pine-fir (SPF). This is not a simple matter due to the low permeability and low moisture content of the heartwood of spruce and pine. The study reported here was designed to compare the treatability of SPF with CCA and borates and to examine ways to improve borate treatment of SPF. Process factors considered were wood moisture content, pre-steaming and surfactant additives. Contrary to expectations, dried rather than green pine and fir appeared to be the best options in terms of treatability with borates but a two-week storage period was still required after pressure treatment with both 4 and 8% solutions to meet American Wood Preservers' Association standards. Based on the rate of movement of borate, dried spruce would be expected to meet the AWPA penetration requirement after 6 weeks storage. British Wood Preserving and Damp-Proofing Association specifications were achieved in dried spruce, pine and fir immediately after treatment. Neither pre-steaming nor the addition of didecyldimethyl ammonium chloride (DDAC) gave any detectable benefits in terms of preservative penetration in alpine fir and lodgepole pine. There was, however, a detectable improvement in treatment of spruce resulting from the addition of DDAC to the treating solution. A summary table of recommended treatment options was developed as a result of the research undertaken in this project.