The ashtray patent — covering an ashtray with an attached moisture-maintaining sponge to ensure more complete extinguishment of cigarettes — is perhaps the most temporally specific of Kenner’s inventions, tied to the era of widespread cigarette smoking that has since declined dramatically in the United States and many other countries.

But it is worth understanding on its own terms, as an expression of safety thinking applied to a common domestic object.

In the 1960s and 1970s, when Kenner was developing this invention, cigarette smoking was ubiquitous.

It was permitted in offices, on airplanes, in restaurants, in movie theaters, and in virtually every domestic space.

The ashtray was a common household and public object, used constantly, and cigarette fires — fires started by incompletely extinguished cigarette butts, either in ashtrays or on other surfaces — were a significant cause of residential fires and fire-related injuries.

The specific problem Kenner addressed was the incomplete extinguishment of cigarettes placed in dry ashtrays.