I extrude 1" square , long tubes, out of dark clay, brush 2 sides of it with white slip enough to cover all the brown, cut them in 3" sections, stamp a texture on opposite sides and put a hole in one top edge and a number on it. That way I get 2 colors with one test. adding the black stripe is a good idea. will start doing that..
If I like the glaze, then I put it on a small pot several times before I use it on something important.