"Mushrooming" at the end of your wick is simply carbon buildup and may happen from time to time. It is typical of core-less/lead free wicks. To quickly and neatly trim your wick, we recommend turning your cooled and hardened candle upside over a garbage bin where you may simply trim or pinch the excess wick to 1/4 of an inch. Prior to relighting, make sure you clean away any soot or debris from the candle surface.