A vacuum chamber is a very handy tool to own. Mine will soon double duty as a reverse (female tool) vacuum form system. I just need to swallow hard and buy that fiber-glass kit to finish the rig.
Clear rubbers like polyurethane and elastomers are thick like honey. If they get bubbles during the mix or even the pour, they can't just rise up to the top and pop. The need help. They need to pulled up and expanded to the point where their surface tension is too thin to support them.
I made a video on degassing if it helps.
https://www.youtube.com/watch?v=gnMl3n9TwqI
I don't degas anywhere near as long as in my video anymore as I have learned that you only need between 2 and 4 minutes with the product I am using. The resin will actually boil under vacuum, and this helps the exotherm kick in. Given the limited potlife it has, you don't want it gelling up during the pour.
Having said that, when I did the texture and splatter on my V2s, I mixed and degassed, then let it sit for an hour before working it. It was thick and I was able to get a pretty cool result by taking a small pointy stick, dip it in the gel state urethane and touch it to the sole of the shoe. It would string really fine and leave a small pimple on the initial point of contact. Very time consuming though and why I will add texture to the master part.