Metal substrate with insulative coating thereon and method of making the same

A method comprising:

• a first step of spraying an insulative coating onto a corrugated metal substrate at a distance ranging from about 6 to about 12 inches to provide a first layer amounting to about 10 to 20 weight percent of the total insulative coating to be applied so that build up of the insulative coating does not occur in the valley of the corrugated metal substrate and cracking of the insulative coating does not occur during drying of the insulative coating, and thereafter a second step of spraying said insulative coating onto the first layer at a distance ranging from about 3 to 6 inches, wherein said insulative coating comprises .gamma.-alumina having at least 10 percent by weight particles larger than 20 micrometers, about 0.01 to about 0.03 weight percent of a catalyst, and about 5 to about 10 weight percent pseudo-boehmite gel;
• drying said insulative coating;
• applying an overcoat of polyvinyl alcohol in water to the insulative coating and drying the overcoat;
• and
• stacking a plurality of folded metal substrates, each substrate having the insulative coating and overcoat thereon, on top of each other to build a monolith for a catalytic converter.