"Did you know?" - Unravelling the Incidence and Value Impact of Resin Blemishes

from Keith Mackie - CEO - Solid Wood Innovation (SWI)

The value of appearance logs is impacted very heavily by resin blemishes.

Resin blemishes come in many forms; (resin pockets, resin streaks, resin blemishes, resinous heartwood & resin canals) and whilst they are generally not a problem in structural products, they cause major value loss in appearance manufacturing.

The appearance of resin features (see Log B) on cut log ends is a sure indicator of resinous defects throughout a stem. As a general rule, if there are 2-5 resinous defects on a cut face then there will be approximately a 40% drop in value and it will not be sensible to cut appearance products from it (and cut patterns more suited to green lumber products would be more appropriate.)

Research over the past 5 years by WQI (now Solid Wood Innovation - SWI) has helped unravel the causes for resinous defects, their prediction in various regions in NZ and locations in stands and some relatively simple segregation rules and replanting decision tools.

More detail will follow in future issues of Wood Matters.