I decided that since I thought I have JUST enough left over mold rubber, that about the only thing small enough I could use it for is that grotesque keystone, so I got the mold out and filled it with water to see how much it takes to fill it, just about one gallon. It looked like I might have just a hair less than one gallon of rubber left, so I mixed it up and got every drop out of the containers I could and poured it in, and it was about a pint too little, but an old trick of floating something weighted right like this plastic drink cup in the liquid rubber, would take enough displacement to raise the liquid up a little. It did that, didn’t get it to the top, but its filled enough the complete design is covered.
Next thing I need to so is make a form to pour the molding plaster into to re-create the 4″ deep backing this had originally.
So, pretty soon I can make this one in fired terra cotta too.
The original this was molded from I removed from a building around 1977 that was at 1 West 111th St in NYC on the corner of 5th Ave, the buildings that were there have been replaced by this new one.Now I need to set up to cast the 4″ deep plaster backing for this.
I like this pourable rubber, it’s also a lot less expensive @ $105 for 2 gallons than what I use for brushing-on molds, and for these use once items it doesn’t need to be premium rubber.
The big issue is being pourable it’s really only suitable for relatively small or thin plaques because it would take a lot to fill larger or deeper pieces.
Now I have the backing form made for this, I’ll have work to do to it yet.
Making the wood form to pour the plaster in was a bit more involved than other pieces as the bottom of the keystone is arched upwards as this was originally over the top of an arched window. I had to shape a piece of scrap wood to fit the curvature.
If I use some clay on the sides to get a texture, smooth and fill gaps etc the plaster form needs to be damp and making the plaster molds’ 4 side pieces has to be done while the clay is still kept moist so the clay doesn’t shrink.