That's a Big Soup Pot

15 January 2022

Boiling Arbutus Wood

Green or fresh cut Arbutus wood retains so much water that it will sink when submerged into water.  When Arbutus wood is left to dry out it can severely crack so much so that it becomes unusable, this may have been a deterrent to some wood turners. We rough turn green Arbutus into rough turned bowls and hollow forms following the 10 % rule. The wall thickness is left at about 10% of the bowl diameter this allows the bowl blank to be re turned once dried with enough wall thickness to allow for warpage and waste removal to end up with a uniform wall thickness. If these rough turned Arbutus bowl blanks were allowed to air dry as most woods would be dried, they would severely crack. The process of boiling the Arbutus for about 1 hour per inch of thickness does something to the wood structure that mostly prevents the wood from cracking as it dries. We typically boil a full 60-gallon stainless kettle for 6 to 8 hours; it takes close to 3 hours to bring the water to a boil. Once the boil is completed, I sometimes remove the blanks right away and allow them to cool, other times I leave the blanks overnight in the kettle where they cool down far more slowly. Oddly it seems this later method causes the wood to absorb more water from the pot as the water level drops overnight but the bowls seem to air dry quicker than when I remove them right away. Once the bowls are boiled if they air dry too slowly with no air flow mold will develop and stain the wood, if there is too much air flow the chance of cracks developing increases. We use a combination of a fan with a timer and a dehumidifier 24/7 to control this process. Typically, the blanks can be re-turned in as little as 6 months of drying time but once you have enough rough blanks prepared ahead you can allow them to dry longer and prevent a warp in a finished piece.

Bringing home the new to us stainless steel boiling kettles.

Our first boil kettle was an old 5 gallon pail, this was soon too small

The small pail was upgraded to a 45 gal drum, this held more but imparted a black color to the outside of the Arbutus from the metal, stainless is the way to go. It was also a little precarious on the stand.