I feel so old ....

The above frame is a variation on a design known as "Taos". It is being used here as an example of the use of rottenstone. Rottenstone is a very fine abrasive powder, a traditional polishing powder. Frame and furniture finishers have another use for it. It is the exact shade and consistency of ... dust, and is used to simulate a dusty surface. It also slightly "cools" a finish, and slightly dulls a finish, though if rubbed off vigorously it will polish the surface, leaving a contrasting, cool dryness in the recessive areas. See the soft, gray dusty areas; that's rottenstone, adhering to the underlying tone.

I stopped at two high end paint stores today, looking for rottenstone. It used to be a common product. At the first store, the young clerk had never heard of rottenstone. He was probably knowledgeable about latex paint, though. Or not. The second store had a clerk my age, maybe, but he had only started working in the paint store about ten years ago, ... so ...  not a clue.

Rottenstone is one of the subtleties of fine finishes. I routinely mix a little dry pigment of various colors into some rottenstone to alter the overall color and effect of a finish. Once a tone has been applied, ( a colored wash ), and is dry, rottenstone may be dusted on, then off. I use one of the old style aluminum salt shakers to shake onto the surface, then brush it overall, and either vacuum, or blow off with compressed air.