The refining skill takes a raw resources and processes them into refined items used in crafting. The proper refining station is required in order to process the materials. For example you will need a smelter to refine ore into ingots, a woodcutting station to make lumber, and the leatherworking station to tan hides.
There are 5 refining stations: Loom, Smelter, Stonecutting Table, Tannery, and Woodshop.
Each station plays a different role in refining and has to be upgraded to refine the higher level materials. It is up to the company that owns the town to start the upgrade process and then it is up to the players to help in upgrading through town quests at the town project board.
The companies that control the town also control the refining taxes for these stations. Make sure to keep an eye on this when refining materials.
A Tier 2 station can refine up to recipe level 49.
A Tier 3 station can refine up to recipe level 99.
A Tier 4 station can refine up to recipe level 149.
A Tier 5 station can refine up to recipe level 200.