The best material for a shim is a thin piece of maple veneer. Most bolt-on necks are made of maple, so it makes sense to make a shim from the same material. The wood can be easily shaped to fit the neck pocket and angled to the proper degree. I typically start with a piece of maple about .060 thick.
Lignin is a class of complex organic polymers that form important structural materials in the support tissues of vascular plants and some algae.[1] Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily.
Definition of indican. 1  1 : an indigo-forming substance C8H7NO4S found as a salt in urine and other animal fluids; also : its potassium salt C8H6KNO4S. 2  2 : a glucoside C14H17NO6 occurring especially in the indigo plant and being a source of natural indigo.