Isopropyl alcohol is mainly used as a disinfectant in the cannabis world to clean pipes, bongs, rigs, and tools, as it does a good job of removing sticky resin. In the past and on the illicit market, isopropyl alcohol has been used to make hash, although this is not recommended because it contains toxic substances not safe for human consumption. Ethanol alcohols, such as liquors, are safe for human consumption and are recommended instead for making hash.
Many people want to know if 70%, 91%, or 99% isopropyl alcohol is better for cleaning your pot-smoking devices. If you experiment with different strengths of isopropyl alcohol, you might find that the higher percentage cleans your bong faster. A 70% may work; it just may take longer. It might help clean your bong if you add 91% isopropyl alcohol and some coarse salt, then give it a good shake. Rinse with soap and water to remove any alcohol residue.