Hi, very new to resin casting, working on a project suspending various objects inside cube shaped blocks of resin. I’m using a cube shaped rubber mold. I’m noticing I get a pretty consistent issue where the top corners of the cube (those at the top of the mold, which are exposed to air as the piece dries), come out rounded, even though I fill the mold evenly to the top when I do my pour. What is causing this and what are some methods I can use to avoid it / fix it after it happens?