all the above is spot on. A hot mold will pour a nice jig, but a cool mold is a frustration til it gets hot. I sometimes forget to put the mold up top and get ready to pour and have to heat it. I lay the mold on it's side and pour the side panels once or twice each side to get it going, and let it sit a minute or two to absorb the heat. Take these and put them back into the pot and they re-melt right away. The hotter the mold, the easier the pour. Also, put candle smoke on all the cavities you plan to pour. It acts like grease to the hot lead, helping get the lead into smaller areas. Big difference in my molds.