-The sign or prop you want to age
-An old chipbrush, or new unloved chipbrush
-A fancy glass palette or paper plate
-Base paint (black or dark brown)
-Patina paints: metallic copper, dark brown, forest green, teal, and a light gray
-Water & cup
-OPTIONAL: Spray paints (brown, copper)
Prepare your foam surface the same way you did for the gravestone. If you are reading posts backwards, that'll make sense when you get to the next article. Another peekaboo at the process: Note that I moved the letters while carving to line up a bit better and included notes as to where my curves got wonky while drawing to improve upon them while I etched them into the foam. I wrapped a bit of string around my Sharpie and held it at the same length at each corner to get evenly sized curves.
Once thoroughly based, I spraypainted my sign brown. "But wait, J!" I imagine you shouting needlessly. I'm right here, guys. "You said the paint would eat the foam!" Yes, I did. But Once it has been painted, the foam is protected and you can spray to your heart's content. The bonus trick of why you would want to spray paint raw foam will still have to wait. Next spray layer was a hammered copper I have from some previous projects. Feel free to replace any references to spraypaint to craft paint if you like to spend time basing things or live in a fascist police state and are under the legal age to buy spray paint.
Next, you'll want to watch this informational video on a good rust technique. The wet blending and stippling are exactly the same, only substitute your colors as follows: Dark Brown replaces black, Forest Green replaces brown, and a bright teal replaces the orange. Your palette should look like this, only way more paint:
Very green, and you can see the copper stipple underneath. Let it pool in your carved letters or other recesses and flow down onto everything else. I tip it completely upright a few times to help it flow. Other times, I spray the surface with my optional spray bottle and flick paint at the sign to get blotches and speckles. By the end, I've added some gray to my washes and have lightened them more towards a light blue and make a last pass or two with thinner washes.
If you want your prop to have been lost at sea or abandoned to the rain for decades, you're done. I was concerned that my letters didn't stand out as much as I had hoped, so I added another layer: Once the washes are completely dry, I load up my palette with copper craft paint and stipple/drybrush straight copper around some of my carvings to help define them and bring the copper back. A lot of signs on buildings appear to have the letters still free of patina years later, and I wanted a more mottled appearance, so it works both in research and practicality.
I found the beaded foam texture helpful to sell the cast copper and it aided the pitting effect on the patina. If you like, give this piece a matte or satin spray layer to protect the washes, as they are in the most danger of being affected by the elements.
Classy, isn't it? Let us know what you think of the technique and please share your copper projects with us.