Variations within species and grades: In both hickory and pecan, there are often pronounced differentiation's in color between spring wood and summer wood. In pecan, sapwood is usually graded higher than darker heartwood. Pecan and hickory are traditionally mixed by flooring mills.
Hardness (Janka): 1820; 41% harder than Northern red oak. Pecan is slightly softer than true hickories.
Dimensional Stability: Pecan, average (change coefficient .00315; 15% more stable than red oak). Hickory, below average (change coefficient .00411; 11% less stable than red oak).
Durability: Combination of strength, hardness, toughness and stiffness found in no other commercial wood; exceedingly high in shock resistance.
Sawing/Machining: Hickory species’ density makes it difficult to season, machine and work with hand tools.
Sanding: Difficult to sand because of density, and because light color makes sander marks show more than on darker woods.
Nailing: Good holding ability; prone to splitting.
Finishing: No known problems.
Information is from The National Wood Flooring Association
"Wood Species Used in Wood Flooring"