How many layers of insulation cotton to be used for powder coating baking oven

Mind you have to achieve a minimum thickness of 15 centimeters, to buy bulk, good thermal insulation, and must be compacted, it is very important. A square meter of good powder and good spray gun as long as 0.1kg powder. Ordinary powder and ordinary spray gun need 0.4-0.5KG powder to achieve. If it is a complex shape of the workpiece, the amount of powder will be more.