With the failure of the last plaster thing, I’m trying again. Geoff suggested doing it it two parts, so, forming the interior space, then soft soaping it, so that I can cast more plaster over that and cut the exterior shape. I was going to dye the interior shape with food dye, so that I could see it, but that was a miserable failure, as you can see below. That white bit of plaster is dyed with an entire bottle of Sainsbury’s food dye, and I know you can tell that it’s blue.
After much running around to find something that could work for dying the outside part so that I can see the difference while I’m working, I happily ran into a friend from textiles who gave me some concrete dye that did the trick brilliantly. Though my plaster mixing skills are much too rusty, and while it worked, it was bubbly, and I had mixed it badly, so I have to do it again.