What is the name and formula of that clay which is spread on wire guaze?

Answer 1

Wire gauze is typically used in laboratories to spread the heat from a Bunsen burner (trivia: invented circa 1854 by German chemist Robert Bunsen) flame evenly over a wider area than the raw flame could cover. As part of the design, a ceramic disc is bonded to the wire. The companies that make these things seem obsesed with not identifying the type of ceramic that is used other than that it's asbestos-free. It's doubtful that there is a specific chemical formula for it, but I'll turn the floor over to whomever can positively identify that stuff.

Answer 2

The clay is called alumina clay and its chemical formula is Al₂O₃. It is used to protect the wire gauze from direct heat during laboratory experiments.