Gathering brings in the raw goods. Refining makes the common materials from them, and refining a common one again with an additive makes the uncommon ones. Production takes them from there.
Uncommon wood, refined from Maple Timber with Sooty Bark by Milling at level 20 (recipe).
One Hard Maple Timber takes 12 Maple Wood, 1 Sooty Bark, and 8 Creosote.
Refined further into:
Production takes it, or its forms, in 235 Carpentry and 4 Tailoring recipes.
What it adds to gear parts made from it: