Abstract
Hinoki (Chamaecyparis obtusa Endl) has been used in Japan for thousands of years owing to its excellent mechanical properties and resistance to biodegradation. There is an increasing volume of plantation Hinoki coming on the market. While old-growth Hinoki is known for its decay resistance, there are questions about the durability of the faster grown plantation material. There is increasing evidence that second-growth plantation heartwood of some species is less durable than old-growth material, but this has not been studied with Hinoki. The durability of second-growth Hinoki heartwood from four growing regions was assessed in laboratory tests against two brown rot fungi. An additional test was conducted to determine the amount of extractives present in the wood. Heartwood from these plantations was highly decay resistant and comparable to western redcedar (Thuja plicata). Hinoki from Shikoku and Kyushu had the least mass loss for Gloeophyllum trabeum (4.73%) and Rhodonia placenta (6.72%), respectively. These results, however, were poorly correlated with extractives content. While further tests are underway, the results support the continued use of this species in exterior applications.