If you have ever looked at Tlingit paintings up close, particularly the bentwood boxes, you will be amazed at some of the fine lines the painters were able to achieve! Much of the Tlingit artwork that was collected in the late 1800's and the turn of that century are masterpieces because of the introduction of metals. However, even prior to that, painters were able to fashion paint brushes that allowed them to paint hair thin lines.
I really appreciate the steadiness of the hands that painted some of those fine lines. Even though I have factory made brushes and paints, it requires concentrated and sometimes intense focus and I still don't get my perfect results.
I paint on birch because I like the color, especially after I stain it with a light tan, such as "pecan." But one drawback is the cellular structure leaves a porous surface even after I sand it with progressively finer and finer sandpaper. That gets fairly tricky when it comes to my fine lines. Here's some of the painting I'm talking about: