Application of wood-based products as construction materials is one piece of the big puzzle to mitigate climate change. Wood is susceptible to biological deterioration. Environmentally motivated legislation is making the use of biocides less attractive from a commercial perspective. Ideally, a wood modification technology should be of low cost, water based and make use of thermal curing. This research has focused on the potentials for esterification of sorbitol and citric acid in an aqueous-based modification process. This article summarises decay performance results from studies performed at NIBIO when using sorbitol and citric acid (PolySorb) for wood modification at different stages in the ongoing process development. Main findings from these studies were: 1) curing at 103°C was not sufficient for the polycondensation reaction, curing at 140°C seems to be sufficient, 2) a curing time of 9 hours seems to be sufficient, 3) PolySorb-treated wood above WPG 60 show good performance against decay fungi, 4) there seems to be a decay threshold around WPG 60 (i.e. no increased performance at higher WPGs), 5) even if the samples were leached before decay testing something is leaching from the samples during the decay testing. Further testing is needed to understand this peculiarity of 5).

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