Some are drawn on an aluminum frame that Bremner constructed and covered with sanded gesso. The final product is unlike paper behind glass. It is an object with thickness and structure like a stretched canvas, and has a similar weight.
Aluminum sign board, which is an aluminum plastic sandwich material, is light and accepting of gesso. He's experimenting with this material as a drawing surface with and without a white gesso background for the pencil marks.
This is another drawing series in progress