March 3rd 2023 by Dave & Alison
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Dealing with Mold while drying Arbutus wood.
This 3" thick by 24" slab of Arbutus quickly developed a green fuzzy mold a few weeks after being boiled. The wood is then washed with cleaning vinegar to kill the mold and has no other effect to the wood.
The process of boiling arbutus to prevent cracking poses another issue. "Mold" Boiling the arbutus greatly reduces the problem of cracking however it also allows the wood to absorb more water, this does not effect the drying time in fact it seems to dry faster however it does place more moisture on the surface of the wood. This moisture under the right conditions can allow the growth of a fuzzy green and white mold, once you wash or wipe off that green fuzz there are dark black stains and if not attended to these mold stains can penetrate right through the bowl blank.
These arbutus boards were boiled and then air dried for about a week before being stacked in the shed with the fan on a timer 8 hrs per day. After about a week in the shed some mold had developed in part from the damp weather and also because there was not enough air movement to remove the surface moisture so mold developed between the boards. To kill the mold the boards were removed from the shed and washed with cleaning vinegar then left standing along the wall to provide maximum air space around each board for another week. The boards are then re stacked in the shed and monitored daily for the next few weeks.
The arbutus burl chunk on the right was fresh cut and then soaked in water with a small amount of bleach. This piece was stored for 3 weeks in water and once the bark was removed you can see the darkish green staining, I believe this is also a form of mold or decay however it wont have any effect as the bulk if not all of that will be turned away. If any of these stains remain in a piece they seldom are noticeable or degrade the piece. If however the piece is left soaking too long it will become very slimy and stinky and very unpleasant to turn.
There is a fine balance to have the right amount of air flow over the drying wood, too little will result in mold and too much air flow will cause the wood to dry too fast resulting in possible cracking. The process of harvesting Arbutus from the time the tree is cut to the point where the wood is dry enough that mold cannot set in requires patience and attention, once you have reached that point the wood can then be safely air dried for months on its own.