What materials do you use for sketching

In 1907, the retrospective on the work of 19th century post-impressionist georges seurat influenced the development of cubism in a radical way through his painting titled, “sunday afternoon on the island of la grande jatte.” ? ?

The degree to witch the surface of an object seems to have a particular feel is referred to as an object

This medium typically is made of graphite, a crystalline form of carbon: