Rubberwood (Hevea brasiliensis) were treated with a 3% proprietary mixture of borax/boric acid using three different treatment schedules i.e. full-cell, full-cell to refusal and full-cell with 12 cycles of vacuum/pressure. Freshly cut samples had mean preservative retentions of 187 kg/m³, 214 kg/m³ and 178 kg/m³ respectively. Pre-air dried samples for one week had retentions of 252 kg/m³, 308 kg/m³ and 282 kg/m³ respectively. An increase of pressure time from 45 minutes to 90 minutes allowed for slightly higher retention values. Preservative retentions of the core (20 mm² around the centre) from freshly sawn samples were 0.08-0.13% m/m BAE (boric acid equivalent), 0.04-0.19% m/m BAE and 0.04-0.21% m/m BAE for the full-cell, full-cell to refusal and full-cell with 12 cycles vacuum/pressure treatment respectively. Retention values of similar samples from the surface up to a depth of 10 mm were 0.36-1.51% m/m BAE for the 3 different treatments.

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