1, there are two kinds of brush ribs, one is literally like the silk marks left by the brush, which are sparse and dense, long and short. Its stone structure is compact and easy to carve. The other is not as obvious as the trace left by the brush, but it has a little stripe texture, and the locals also like to call it lacing.
2. Thread refers to the spiral continuous convex part with a specific section made on the surface of cylinder or cone parent body.