Movement of boron from ulexite and colemanite minerals in sapwood and heartwood of Cryptomeria japonica

This study evaluated boron diff usion from raw boron minerals ulexite and colemanite with low water solubility in comparison to disodium octaborate tetrahydrate(DOT).Tests were conducted using sugi(Cryptomeria japonica(L.)f.D.Don)sapwood and heartwood blocks conditioned to 30,60,and 90%target moisture content.The blocks were fi lled with the boron compounds through treatment holes and diff usion was observed at three assay zones across the blocks after 7,30,60 or 90-day incubation period at room temperatures.For comparison,ethylene glycol was also introduced into the holes to elevate boron diff usion.As expected,diff usion increased with increased moisture content and levels were higher at the 60%and 90%moisture levels compared to the 30%level.With some exceptions,boron levels did not follow consistent gradients with distance away from the treatment hole.Incorporation of ethylene glycol helped increase boron levels,even in heartwood blocks.Boron levels were higher from the ulexite source than from colemanite;however,DOT treatments resulted in the highest boron diff usion rates as a result of greater water solubility compared to both raw boron minerals.The results suggest that ulexite together with ethylene glycol may be useful in both sapwood and heartwood materials when kept at high moisture levels for extended periods.

Comparative evaluation of boron distribution from ulexite,colemanite and DOT rods in Scots pine wood

This study evaluated boron diff usion from rods made of raw boron minerals,ulexite and colemanite with low water solubility,in comparison with di-sodium octaborate tetrahydrate(DOT).Scots pine(Pinus sylvestris L.)sapwood and heartwood blocks were conditioned to target moisture contents of 30%,60%,and 90%.The rods were inserted into the blocks through treatment holes and boron diff usion was observed at three assay zones across the blocks after 7,30,60 and 90-day-incubation at room temperature.Ethylene glycol was also inserted into the holes to improve boron diff usion.Boron levels increased with increased wood moisture content.With some exceptions,boron in the assay zones did not tend to follow consistent amount gradients with distance from the treatment hole.Boron levels from ulexite rods were higher than those from colemanite rods,with DOT rods with the highest diff usion rates as a result of higher water solubility of DOT than ulexite and colemanite.The results suggest that ulexite-based rods may be useful inthe presence of ethylene glycol in sapwood when wood is at high moisture content for extended periods.