Heartwood
The darker, denser inner wood of a tree, no longer conducting sap — the part most flooring grades are written around.
Grades are written in terms of how much heartwood and sapwood a face may carry. NWFA/NOFMA Clear oak is described as a heartwood-dominant product allowing minimal character marks, while Select permits unlimited sound sapwood.
In black walnut the proportion is stated explicitly: No. 1 Common requires heartwood to be a minimum of 25% of the piece. Since walnut is bought almost entirely for the colour of its heartwood, the grade named on a quote materially changes what arrives.
Related
Terms this one depends on
- SapwoodThe paler outer wood of a tree, still conducting sap when the tree was standing. Permitted, limited or required depending on the grade.
- Flooring gradeAn appearance classification for finished flooring. The standard states outright that all grades are equally strong and serviceable in any application.
Provenance
Where this definition comes from
Framework pillars this term is material to
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