The following recipe for a non-conducting composition has been given for use with steam pipes, etc. In water, mix fireclay with four times the quantity of small coal ashes to the consistency of thin mortar. Then mix equal quantities of dry calcined plaster and Hour, each constituent equalling in quantity the amount of fireclay previously used. Add to the ash mixture. Two coats should be used, with a setting coat outside, as when plastering a wall.