antique arts & crafts vintage, architectural cast iron heating/ventilation register grate

Old, Arts and Crafts vintage, cast iron architectural floor heating register grating. This grate is marked "9 x 12" in raised letter on the underside and measures 10 1/2" wide and 13 1/2" long over the outside edges and it is domed about 1 3/4" high.

This old architectural grate was spray painted copper or bronze at some time, but we think that it has a black japanned or porcelain enamel finish under the copper paint as there are a small chips to the edge. We're not sure how well the paint would strip off and haven't tried.