I have run in to a problem welding some cast iron pieces, and need some advice. I using a stick welding rod without the coating and using my tig welder. The problem I'm running into is the weld bead is porous and won't flow( little holes and craters) and is almost black, Is it too hot, wrong gas, dirty? The rod is for welding cast iron and machinable. It's been said it can be welded this way, but I'm doing something wrong. HelpI