"Aluminium metal dissolves readily in dilute sulphuric acid to form solutions containing the aquated Al(III) ion together with hydrogen gas, H2. The corresponding reactions with dilute hydrochloric acid also give the aquated Al(III) ion. Concentrated nitric acid passivates aluminium metal."...
Sulphuric acid, which is the usual type used for attacks due to its easy availability in DIY stores, is sold in plastic bottles; it reacts with metals like aluminium.
Has anyone heard of safety or security incidents involving metal flasks or water bottles ?
"note to bottle throwing hooligans - always carry a spare couple of lids in your pocket (and remember to aim the thrown bottle at Mr Dean of the Wirrall)"
Seriously though, Flasks ? "health and safety" ? What a load of cobblers.