Knobs 281, 285, 286 & 287
These knobs were made from Cali™ “Fossilized” Bamboo, product 759153 (blond or natural) and product 759154, heated to a caramel color. Bamboo is not wood, but grass. In this product, strands of bamboo are apparently melded together under heat and pressure with plastic resin. As I recall, Cali claims a Janka number of about 5000, very hard. The material has no give, and the 6mm shaft hole must be cut with a 6.1mm drill, or it would not slide onto a pot shaft. I sanded the hard clear finish off the tops of two flooring samples, obtained from Lowes, a local home and lumber center. Then glued the two together with ordinary 5 minute 2-part epoxy, so as to fill any voids, since it was very hard to sand, even on a belt sander.
In two of these knobs, the epoxy failed, splitting apart, either on the application of pressure from the point of the lathe tailpiece, of or with the pressure of the #5-40 set screw applied to hold a 6mm drill rod shaft set in the lathe. This can be repaired by cutting off the epoxy, sanding the mating surfaces of the two halves on a flat block sander, and clamping with superglue around a 6mm shaft coated with paste wax. The 6mm shaft hole had to be redrilled with a 6.1mm drill, and the slight mismatch imperfections turned off on the lathe.
Because the material already has hard plastic embedded in it, and polishes to a fair gloss, only Kiwi neutral shoe polish was used to finish it. With handling and time, this dulls to a pleasing satin finish, and can be repolished if needed. Considering how epoxy can fail to fully adhere, other finishes might require some experimentation. The side grain can have a little iridescence, but note how the end grain of the bamboo looks like micro leopard spots. The contrasting grains make a convenient rotation pointer.