When Wood Looks Like Marble: Inside Spalting

December 12, 2018 tim mcguire

Spalted maple wood which looks marbled in appearance

Ever wonder what's going on behind those beautiful marbled streaks of black running through an otherwise light colored wooden piece? Our in-house spoonmaker, Tim, describes some of the science behind spalting, what makes spalted pieces special, and breaks it all down for us in a quick and interesting read.

A spalted maple pizza peel

Sometimes the root cause or aftermath of a tree’s death can create an awe-inspiring look for a finished product. Take, for example, a process intertwined with tree death called spalting, which can create odd pigmentation, such as light green or pink streaks and splotches, “bleach” darker wood to light brown or white, or—our favorite—create dark lines running through the wood. This last effect creates a stunning contrast—we like to think it looks almost as if the tree put on thick eyeliner for its funeral.

Spalting can occur in almost any kind of tree. It’s a fancy term for what happens when a fungus moves into the wood, sometimes before, but usually after a tree dies. When it occurs in dead and fallen trees, spalting is merely an early stage of the decomposition process that helps clear the forest floor. Spalting can also occur in living trees, particularly if they are already under stress, and be a contributing factor in tree death. Reactions between the fungus, the wood, and insect deposits create pigmentation, while white rot (“bleaching”) happens when the fungi remove lignin, part of the wood’s cell wall that creates pigment. The “eyeliner” effect, commonly referred to as zone lines, is the result of fungi putting up barrier walls to stop new waves of fungi from moving in on the territory.

Spalted Maple ice cream scoop

Don’t worry, though! The fungi responsible for spalting are killed off in the extremely high temperatures of a kiln before we create any of our spalted wood products. And it’s only harmful to trees when they are alive; in most cases, it’s just a natural part of the cycle of life and death. It’s one of the reasons we choose to work only with ethically harvested urban lumber: trees that have already succumbed to, or are in the midst of, this process.

Additional Sources: The Woodplace, KerfCase

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