Water blasting

Sand...blast it!

The use of high presure abrasive for cleaning rust and paint from metal surfaces by projecting it through high pressure water is becoming increasingly popular, being as effictive as dry techniques, but conciderably safer because there are no atomised granules in the air for operator, or bystanders, to breathe. 

Using high-presure water technolegy to project the abrasive also provides extra impact.  Using a venturi system sand is sucked up into the water and blown through a tungsten carbide nozzle, a mixture of abrasive granules, and the water blows paint and rust away in the fraction of the time.