A clean oil burner will always produce best results. Remove any used tealights and clean the bowl with a soft cloth. Grehom oil burners have bowls made from wrought iron and brass, materials that are very easy to clean. It is important to put out the tealight if there is no water in the bowl. Using the oil burner without any water in the bowl can overheat it and in extreme cases may crack the colour coating in the bowls made from wrought iron. If this were to happen, you can purchase additional wrought iron bowls from us. If the brass bowl develops limescale or tarnishes, then rub it with a mixture of salt and distilled clear vinegar to restore pristine shine.