My old house in Rochester NY was designed by my father and built by a custom builder in 1950. The bathroom had linoleum on the floor. But the toilet did not rest directly on the tile. Instead it sat on a rectangular slab of some dull black material. The slab was a few inches bigger than the base of the toilet, and had a gutter groove around the perimeter to catch any condensation or minor leaks. The floor tiles came up to the edge of the slab. I don't know what the material was, but it looked like the stuff they use on the top of chemistry lab benches.
Does anyone know what this thing is called, whether they still make them, and where I can get one? Thanks!