Cool method of cleaning. I sincerely doubt that is rust. I think you need more wick, too. I know i solved all my wicking problems by switching to rayon, but I think you are underwicking your coil too much, and that is a very common cause of popping, spitback and etc. If you feel like it's too much wick, keep it pretty tight in the coil, and then thin out the tails some. But yes, you really need more wick.
Anna