This Claro walnut burl is likely the largest we’ve ever cut—nearly 3,000 pounds. Cleaning it was far more demanding than the maple burls we usually process. Walnut bark is both toxic and acidic; if it contacts your skin and sits, it can cause burns and leave staining similar to henna tattoos. FUN FACT: Walnut bark causes burns and stains because it contains juglone and other naphthoquinone phenolic compounds. •Juglone (5-hydroxy-1,4-naphthoquinone) A naturally occurring allelopathic toxin concen