Several different mixture ratios are commonly used, and all are called piranha. The typical mixture is 3:1.
Other protocols may use a 4:1 or even a 7:1 mixture. A closely related mixture, sometimes called ‘base
piranha’, is a 3:1 mixture of ammonium hydroxide (NH4OH) with hydrogen peroxide. Base piranha is also
known under the name of TL1 cleaning. All are equally dangerous when hot, although the reaction in the acid
piranha is self‐starting whereas the base piranha must be heated to 60°C to initiate the reaction.