Andrew Birkett's nobugs.org
At this point, you are meant to sprinkle “parting dust” over the top of the mould, so that you can easily seperate the two halves later.
Uhhm, parting dust? Oops, I knew I’d forgot to buy something.
Well, what is parting dust anyway? It’s any powdery substance which is going to soak up water from the surrounding area. A quick check in the bathroom revealed a complete lack of talcumn powder. However, the kitchen did contain some corn flour. Okay, it’s not ideal but it might just work! Besides, I’ve read accounts of people who totally forgot to use parting dust, and they got away without it.