text: I use RCX as well I heat it to 70, add FO at 65, and pour it in preheated jars at 38. I find that most of the cracks I used to get before were because of the room temperature. I think it is important as much as the temperature we heat the wax and pour it. If the room is a bit colder I always get cracks on top so I usually keep the candles stored at around 22 degrees.