ABSTRACTInsulating materials of various types are discussed and their installation in air heaters, carbottom, walking‐beam bright annealing, standard, bell‐type, and wire patenting furnaces, and glass leers is described. Data on the savings involved in the use of insulating refractories are given. The characteristics of the materials are uniformity of product, shrinkage and spalling properties, physical strength, insulating value, and thermal capac