Pressure Washing, Sand Blasting, Vapor Blasting
You have to own the right equipment and know when to use it.
Pressure washing is pretty standard in every remedial project. But occasionally you're going to need to remove previous coatings or rust scale before you paint. For that, there's either sand blasting or the latest technology, vapor blasting.
The key to vapor blasting is the flow of a waterborne abrasive, giving a finer finish due to the flushing action of the water. No media is impregnated into the component, nor is there any dust created by the break-up of media, unlike dry blasting, where the finish is produced by sheer force of media impact.