It is rare around here to find second hand corbels so when I see them, I nab them up real quick. These particular ones I bought off a local Facebook charity auction group. They are quite heavy so I'm not sure what they are made of. Cement, maybe?
After a good scrubbing, I primed them with Plaster Paint Company's New Surface. What I love about this primer is that it is a bonding primer and can be painted over within 30 minutes if you are using Plaster Paint Company's paints. I would give it a little longer if you are using other brands such as I did. In Canada, you can find this product at www.plasterpaint.ca and in the United States through www.plasterpaintco.com. The picture below on the left is after one coat of Dixie Belle's new Cotton color. I did 2-3 coats to completely cover and hide.
As I did on the last corbels I refinished, I made my own glaze using a grey chalk paint mixed with Saman water based varnish. I literally just brushed it on like I was painting it and then immediately wiped back off using a damp clean rag, careful to leave some pooling in the crevices. As you see, it also leaves color all over the flat surfaces as well. This is what I wanted to happen. If you don't want to leave color all over like that, but only want it in the crevices, you would need to seal your base color (in this case, white) by doing one coat of top coat over it first and allowing that to dry a day or two.
I finished them off with another 2 light coats of the top coat without the color added . . . just for additional protection.
Aren't they pretty! These are available locally to the Moncton, NB area for just $40 for the pair!