Sand blasting

[Snowtractor]

...is used for thin metals on classic cars as it won't expand the metal just remove paint and rust. There is also glass beads, crushed nut shells ( I think they use pecan ) and several other types of media used in North America for blasting. Chemicals are fine but remember to completely neutralise them or they will eventually eat a hole and they may get in to areas like folds where you will not get them out. The same with water blasting , the water will get everywhere and is a hellova solvent. Ship sides are steel plate with no folds for the most part. Good for stripped down frames or axles though.
Lastly remember to wear masks,preferably clean air supply, as the paint probably has lead and heavy metals in it and if you use silicas the dust can cause some sort of lung/nerve condition.
Sean