Part 1 and 2 of the multi-part mold went fine. However when I switched products to a clear silicone for the outer pieces of the mold I ran into problems. Air Bubbles!
I knew it wasn’t going to go well when I was degassing the silicone in a vacuum chamber. The directions for both this and the other silicone I was using instructed to degas the silicone in a vacuum chamber at 29 bars of mercury. This stuff expanded more than the other product so I couldn’t get to 29 bars without making a huge mess, so it was more like 26 bars. It foamed up like the head on a beer and never broke and settled. After 10 minutes or so I took it out and tried to stir out some of the bubbles, but it was a lost cause. I poured it anyway and the picture above is the outcome. I was able to salvage my previous mold pieces, so I’ve worked out a new strategy and ill give it another go tonight.