Many of those things we hear about are blown out of proportion. The process of blasting creates heat and if you continually blast one area long enough it will warp. So a good blaster will take a longer time to do a panel that is 'crustier' than one that has little to remove. It also depends on what he is blasting and its shape. He will probably start w/ a larger 'medium' and depending on your end result use smaller types and grit size. They can blast w/ steel, plastic, sand, glass and nut shells. It also depends on the type of 'medium' used and mostly has to do w/ an in-experienced blaster. You know the kind, student, summer job, here kid go blast that aluminum door panel off that Allard. An experienced blaster should be very able to blast your work, and it will come out fine.

Gooday
Jim

small wheel moves by fire and rod,
big wheel fires by the grace of god,
everytime that wheel turns round,
bound to cover just a little more ground.