Drying Processed Wood

24th Mar 2024

 This 3" thick by 24" slab of Arbutus quickly developed a green fuzzy mold a few weeks after being boiled. To kill the mold I wash the wood with cleaning vinegar, this does not appear to affect the wood in any other way.

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 affect 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 above 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 won’t 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. Experimenting with your species of wood is key. the process I use here in the PNW for Arbutus may not be the same for other species in other parts of the country.

Most of the woods I process are dried and stored in the basement with a fan on a timer and a dehumidifier that runs 24/7. I boil Arbutus, Apple, Garry Oak after rough turning or processing into boards or mill blanks. I don't boil Big Leaf Maple Burl, Walnut, Yew, as these woods seem much more stable for drying. After I boil a pot of Arbutus for 6 to 8 hours I remove the wood and lean it against the shop wall for a day to air dry. The next step is to weigh, date and identify each piece of wood. I then stack the rough blanks in the basement with stickers for air flow along with a fan to remove the surface moisture. The bowls on the floor are in the drying stage while the two racks are dried blanks ready to finish turn. I don't use any log end sealer or paints etc. on any boiled woods.