Rendering realistically darkened end grain

it’s not terribly difficult to get wood grain oriented correctly on an object however I’ve yet to find any advice on how one would get an end grain that has darkened with the application of a clear coat or oil, ect. A box joint - finger or dovetail is beautiful by the sharp tonal distinctions they expose. As it is now with my rendering savvy one can only notice the change in grain pattern.


I was wondering if some sort of python script could evaluate the surfaces of a rectangular block and assign the two smallest faces as targets for end grain while the remaining four host the regular texture.