Heavy, plaster ornaments.
I'm working on some frames from late 19th. century or early 20th. The heavy, deep, and severely undercut ornaments are in plaster. In order to make replacements, with the materials on hand, I'm basically molding and casting just the tops of the missing ornaments. In the picture above, a top has been positioned with the help of some screws.
Here, I've built a dam of masking tape, prior to filling, through the front, with plaster, the undercut parts. There are wire reinforcements through the "top' castings.
Another ornament top, showing the positioning screws, and the reinforcing wires. The "tops" are resting on the screws, glued into position with cyanacrylate glue.
And the above ornament with the masking tape dam. When the bottoms are filled, essentially I'll be carving the replacement ornaments, using the tops as a guide, along with the remaining parts of the original ornaments.
What you are seeing in the above photos is the original finish applied to this frame. Water gilt karat gold for the highlights; then a bronze powder pigment paint for the body. The bronze powder has tarnished to the point of being dark brown. Sometimes they tarnish to a dark, earthy green. I'm going to restore the karat gold as needed, and then repaint the body, using non-tarnishing mica powders for the gold pigment, in a shellac medium.
In the last two photos, plywood overlaid splines are visible, to reinforce the miters. I've added hide glue where I could, but these are very difficult frames to disassemble, as the ornaments, and wood substrate are often cross nailed, and there are numerous reinforcing nails for the cast ornaments. So, the add on splines.
Musing on the technology to produce these type of frames, I'm assuming that the ornaments were cast using rubber molds, that could be pulled free of the undercuts. Corner ornaments were probably cast last. Interesting frames, and somewhat rare compared to composition ornament frames, though this methodology is the only means to produce these heavy, and undercut ornaments.