Help with some settings

Hello. This is my first post to this forum. I have had the Falcon 2 for some time now. I just got a set of black powder coated stainless steel flasks. Did a burn of 236 inches at 30% power at the 22 watt setting. These are the settings I do ALL of my powder coated stainless steel mugs at and they turn out really good. The flask did not turn out so well. It is still kind of blackish even after cleaning. I know it is off centered. I set the focus to 3mm at the center point (flask is curved). All help is greatly appreciated. Thank you.