Old House Journal stepped up to the plate last month with an article on beautifying old radiators that we bet most brownstone owners will want to check out. We got a kick out of this ad pitching a particularly ornate model:

For beauty, richness and delicacy of ornamentation, elegance of proportion, finished smoothness of castings, appealing senses of lightness and gracefulness, the Verona is simply incomparable. It is a work of art in iron.

The two historic techniques discussed are “polychroming” and “stippling” neither of which we were familiar with. Click through for detailed explanations of effect and technique.
Cut Stone at Green-Wood Cemetery [Old House Journal]