There are different finishes that can be applied to the external aluminum sash which open many different possibilities:
1. a hard-wearing Polyester-powder coat in a wide range of RAL colours;
2. metallic finish in RAL 9006 & 9007, or anodised silver or pale bronze.
Internally there are further choices.
Wood can be treated with a clear lacquer to enhance the warmth of the natural grain, or painted in one of a range of RAL colours to match your interior decor.