Can I retain the bark on milled logs?
I like to slice logs at an angle and use these slabs for fretwork. What do I have to do to keep the bark from drying, shrinking, and falling off the slab?
—Wes Kegel, Blue Earth, Minn.
You'll increase your success by cutting trees while they're dormant, Wes. Trees cut during their growing season have a moist and delicate cambium—the layer separating bark from sapwood. Cut most types of trees then, and bark easily peels off the trunks. For your purposes, harvest the tree in the late fall or winter while the cambium is firm.
That's just the start, though. The cross-sections shown above began to check within days after being cut. To prevent excess shrinkage and make sure the bark stays on, soak the slices in a mixture of 30 percent polyethylene glycol (PEG) and water until the PEG replaces the water in the wood cells. Soaking times vary by thickness and wood species, but cross-sections quickly become saturated. Start with a soaking time of three weeks and experiment from there. After the wood is saturated with PEG, remove it and allow surface moisture to evaporate before working the cross-sections.
A downside to treating wood with PEG is that you'll need to seal the wood against moisture to prevent the chemical from leaching out. Protect your finished projects with two coats of polyurethane or, for a more natural look, Watco Danish Oil.
Polyethylene glycol is available from woodworking specialty stores, or Lee Valley Tools, 800/871-8158 or leevalley.com.