The edge of the wall is slightly thicker than the rest or it, reason being, i am always scared that if the mould is tight upon trying to open it, i may have to crank on it, and do damage if its thin. ( i know in reality from doing these its unlikely for that to happen )
Also i make my moulds fairly thick for a couple of reasons, 1st and foremost ...... stopping them breaking, especially with me moving, i want them strong.
also rightly or wrongly, i am under the impression that because latex dries by the moisture being sucked out via the plaster, if the mould is thin, the moisture will stay in the surface and shorten the lifespan of the mould, my 1st mould is 5 & 1/2 years old and still ok, and i think the fact that is was thick and the moisture possibly gets spread out, means the details hang around alot longer.
could be rubbish but hey