CT imaging of Lindner tested, burnt timber

The durability of fire-retardant materials used for wooden structures and wood-based products can be evaluated on small cut-out samples with the so-called Lindner test, which is a standard procedure in Hungary where 1 g of hexamethylene-tetramine is burnt under the wooden specimen and the mass loss is measured. For further spatial information about the burnt part of the samples, the specimens were CT scanned after the Lindner test. The goal was to evaluate if the charred part can be properly segmented in a CT image set and if the two measurements combined are precise enough to provide charring rate data. With the segmentation of the CT image sets, the burnt volumes could be separated properly in each case even when knots were present. Spruce sample provided the most consistent results regarding the mass loss/burnt volume. This is probably due to the uneven ring spacing and other inhomogeneities in the density of oak and ash.