A growing proportion of harvested Scots pine (Pinus sylvestris L.) timber originates from the first or second commercial thinning stands. There is a need to find economically viable and high quality wood products that can be manufactured from this raw material. Small log volume means not only demands of increased efficiency for material handling in logistics and manufacturing processes, but also challenging wood properties such as high proportion of juvenile wood and sapwood. Due to these facts, products made of small diameter logs are prone to twist and check, and have poor durability against weather. These shortcomings can be improved by a number of preservation methods. In this study, we concentrated in pressure impregnation with copper based preservative, and pine oil impregnation. The objective of the study was to define the modulus of elasticity (MOE) and modulus of rupture (MOR) of non-treated, pressure impregnated and pine oil treated fencing posts in static bending. The material originated from five stands in south-eastern Finland. We prepared two diameters of round posts (80 and 120 mm), and two square-sawn dimensions (50 x 50 mm and 100 x 100 mm). The material was divided into three treatments: 1) not impregnated, 2) pressure impregnated into AB-class with copper-based preservative in commercial process, and 3) impregnated with pine oil using the process of Ekopine Ltd. After the impregnation, the specimens were further divided into two groups. The first one headed straight to the bending tests, and the other group was subjected to weather exposure test. After the weather exposure test, also these specimens were tested in bending. The bending tests were done according to EN 408. Unlike expected, both MOE and MOR of square sawn posts were higher than those of round posts. The AB class pressure impregnated specimens had, on average, slightly lower strength than the other treatments. This was also the case with stiffness of round posts, whereas the square-shaped AB impregnated specimens had almost equal stiffness compared to the non treated and pine oil impregnated specimens.

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