I have tried a couple of times to make a shell candle with a picture on it. Well, I think I am doing something wrong. When I pour the wax into the mold the picture just seems to float and then when I pour out the wax and leave a shell on the inside it just seems to be clumpy and the edges are not smooth. Are there any instructions that I could follow to make a successful shell? Or is there a class that I could attend to see how this is done?