I included my node setup for the material I'm painting on. It is strange, but when I paint directly on the mesh my black paint shows up only as a light tint that never gets any darker unless I release the pointer and reapply more paint on top. If I do this about 8 times I get a very black color. On the Image Editor window, however, I can keep the pointer pressed down and just scribble back and forth and the paint accumulates correctly making a darker and darker area without having to release and reapply and release and reapply several times. Is this a bug, or more likely I don't really grok texture painting. Can someone assist?
By the way, I tried this on the make-up layer texture as well as the skin texture layer. Same result.
Here I show you my current brush settings and in the 3D view window, you can see 3 blue sections on the model's cheek. The far left one is the result of 4 or 5 passes of the brush (click and hold, scribble scribble scribble, release, repeat), the middle one is the result of scribbling in the editor window, and the far right is the result of scribbling on the model in the 3D window in just one pass (click and hold, scribble scribble scribble, release). When I have "accumulate" checked, shouldn't I be able to get the middle and left result by doing what I did in the far right example? Why does it remain so pale no matter how much I scribble over it? Why am I having to release and reclick to add more paint?