Near Success!

Well, the mold isn't perfect. I finally got some burlap and slathered it with plaster to form my shell. That worked beautifully. $5 of burlap makes enough bandages for about half a dozen molds the size I'm doing. Maybe more. The key is getting the plaster to the right consistency. Normally I do 2:1 plaster to water by weight, but I added a bit more water this time to keep the plaster liquid. It worked pretty well, but you still need to work quickly. Adding more water to the plaster mix will work, but only for a little while. Once the plaster has set past a certain point, it will just turn into slimy clumps and that's not good for anyone. Once you get the burlap soaked in plaster, you can just sort of slather it onto the mold. I think I've described the process in detail before so I won't bother you with it again.

This works pretty well. The burlap is thicker and heavier than the gauze you normally use for plaster bandages and so it doesn't like to mold as closely to the model. You can fill in the gaps with thickened plaster pretty easily. For this process you don't need a perfect fit, just enough support to keep the silicone from deforming. Make sure you leave wide enough edges to clamp the two halves together. You could probably do this entire process without the bandages at all if you really felt like it. A thicker mix of plaster would make it pretty easy to scoop out and apply with your hand. I didn't do this, but I did patch some holes in the mold this way and it worked fine.

So on to the silicone. The white silicone seems to have worked beautifully. It is strong, flexible, and maintains shape quite well. It looks like I missed a few spots on the model with my release agent, as there was some minor sticking. This isn't a huge deal for what I'm doing, but it would be pretty disastrous for some projects. Make sure your release agent layer is very complete to avoid this. Also avoid touching any part of the mold with your bare hands after you've applied it. Turn the piece using the edge of the base if you need to. Short of the little sticky bits, everything looks great. I'll have a few rough patches on the candles to clean up, but I anticipate that they'll turn out well. I will take some pictures at least of the completed parts before, during, and after the pour. We just got a new camera and I think I can rely on myself to take every chance I can to play with it.