Q: We have substituted Wenge from Africa for black walnut, but now supplies have dried up. We are considering Peruvian walnut. What can you tell us about this wood in terms of processing?
A: There are several walnut species in Central and South America. We call them "tropical walnut." In general, these walnut species are darker than American walnut and may have a slight purplish cast. Tropical walnut may also have a coarser texture. The density of tropical and American walnuts is identical, so processing of dried wood will be identical. In-use shrinkage of tropical is less than American - it is more stable.
The major problem with tropical walnut is drying. We had some 8/4 that was air dried for 12 months and had core moisture contents in excess of 50 percent MC. After two months of kiln drying, the core was still above 30 percent MC. Problems were less with 4/4, but even after 90 days of drying, some 4/4 pieces still had wet cores (or wet pockets).
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