The surface is burnished very well to get a smooth surface and ads graphite to make it shine in a metallic way, then is painted with matte squares.
About the artist:
Now on his fifties Isrrael has been doing pottery all his life. Recently, his more dramatic pieces are done as follows: when the piece is still wet he takes away little parts of clay leaving little holes on perfect parallel lines and then when the piece is dry he fires it on a tent of wood covered with a plant pot to get an oxigen reduction firing, the result is an striking matte black pot. On other pieces he polishes it to get a perfect shin metallic look.