how do i increase timber quality?

[halby]

[halby]

like the quality of steel is based partially on the quality of iron, and bauxite, and the quality of iron is based on ... nothing, it's just always 62... ?

the fact that it's not 100 implies i can raise/lower it somehow, but i can't see how? maybe different mines have different quality of iron? or maybe there's a technology i get at a certain date that improves mining efficiency? or maybe i need to create a refinery to refine the raw iron into something higher in quality?

same q with all raw materials, timber, silica, etc.... either their quality is static, in which case it's confusing that it is some seemingly random and different every time number like 48 or 62 or whatever... or it's dynamic, in which case I don't know how to influence raw resource quality... heeelp

[David]

Actually the quality ratings of all natural resources including timber are predetermined in their natural reserve sites. A timber site with higher quality will be more costly to acquire to than one with lower quality. So if you want to have timber production of higher quality, you can browse the cities and find the site with the highest quality to acquire.