More to explore:
Drawn to Surface: How to Make and Use Underglaze Pencils, Crayons, Pens, and Trailers
Ceramics by the ceramic artist Mel Robson, based in Alice Springs, Australia. His link is feffakookan.blogs...
What is Glaze?
underglaze with black, transparent glaze over it
Black and white ceramic vase.
Texture and glaze
Lovely surface decorating techniques - video