Abstract:
Disclosed is a honeycomb support structure comprising a honeycomb body and an outer layer or skin formed of a cement that includes an inorganic filler material having a first coefficient of thermal expansion from 25 C to 600 C and a crystalline inorganic fibrous material having a second coefficient of thermal expansion from 25 C to 600 C. Skin cement composition controls level of cement liquid/colloid components, for example water, colloidal silica, and methylcellulose migration into the substrate during the skin application process to form barrier to skin wetting and staining during the washcoating process.