Why would you want to clean your Hookah bowl right after you smoke? This task might seem tedious while you are relaxing after a session with friends. But with the research we have conducted, the black residue that remains on your bowl is Tar. That is why, when you try cleaning it days later, the black junk becomes impossible to come off. The tar may have derived from two things: the coals and tobacco. Most Hookah Tobacco packages contain tar as it spells it on the container. So once the coals begin burning the tobacco, the tar begins to produce leaving it on the bowl. Also, coals serves as the catalyst to produce tar, and the tar derived from coals are considered fairly toxic because it may contain a high benzene level. Furthermore, Tar in tobacco is a cancer-causing agent. The tar in the tobacco is what scientists believe to cause lung cancer. Despite whatever you smoke out of your Hookah, if tobacco was placed in the bowl, the tar will always remain on the bowl burning as you inhale these toxins in your lungs. That is why we recommend to clean and scrub your Hookah bowl after you finish and to replace a bowl at least once a year.