This is an airbrush that can be used to emulate pores or give a bit of noisy texture. I use it on skin but it may be helpful in other areas, too.
Set the brush to any color and apply on a layer above the skin.
Here, I set the brush to a white color. As such, it is more noticable on darker areas. If a darker color was picked, it would be more noticable on the lighter areas.
Can you tell I like using textures? c: