I think what you are experiencing by doing that is you are heating the hook. By heating the hook, and putting it in the mold, you are now allowing the lead to flow around the entire hot hook. There are no cold spots in the mold. The process you found is common, especially on cold days and is used especially on bigger hooks. I put all my hooks in the winter time, on a black tray, and put a 100 watt light bulb over the hooks to keep them warm. Many guys put them on a hot plate to keep them warm, you can also lay them on top of the flat part of the pot to keep them warm. As far as sooting hooks and molds, I personally do not do this. I do not believe this helps, however that is the way that I do things. If it works for you then by all means keep doing it. You will find that as you pour more and more, there is no one way to do things. You will find that what works for you may or may not work for someone else. Also remember that all of the help you get here are only guidelines. We are all guessing at what a problem is we are not there with you to see what you are actually doing or what is happening. Some info will work some of it won't. However like you posted, please always give everybody feedback, so we can all learn from the newbies toall of us seasoned(stubborn) pros.