Paint on a Dogoszhi Black-on-white sherd at about 10x:

Below: Paint on a different Dogoszhi Black-on-white sherd at about 40x (this paint is thinner, grayer, and did not soak into the sherd well. It is weathering away and looks almost like lichen (but it isn't):

Below: "Paint" on the asbestos floor tile at 10x (it's really tar used to glue the tile to the floor):

tar at 40x: