Computerized dynamic swellometer evaluation of oriented strand products

A dynamic swellometer was assembled to determine the dimensional changes in wood and wood composite products when submerged in liquids such as water. The dynamic swellometer consists of three major components: I) a swell cham ber for securing and immersing samples in water so that no floating can occ ur during testing; 2) a series of eight linear transducers that measure sam ple swell in 25.4-mu m increments; and 3) a computer with custom software t hat records measurements at specified time intervals. The swellometer was o riginally designed for solid wood and fiberboard, but this work reviews the swellometer results of thickness swell for nine commercial oriented strand products manufactured by five companies. These strand products included va rious North American wood species in eight oriented strandboards (OSB) and in one strand lumber-type material. Two of the strandboards were marketed a s siding, one as underlayment, and five as sheathing. The swellometer resul ts were compared to results from a more conventional-sized OSB test sample in water submersion for 2 hours, 24 hours, and 48 hours. After 48 hours, bo th tests exhibited a leveling of the thickness swell curves, with the range by the swellometer between 7 and 37 percent and the range by the more conv entional method between 9 and 50 percent, depending on strand product type. The dynamic computerized swellometer in this study offers continuous monit oring of swell values over time without hand measurements, saving time and costs. The specimen size could be adjusted to provide the desired informati on needed by product type.