We have a large tank that needs to be painted. One always considers sand-blasting, but finding portable services for blasting seems to be hard in our area. So, we're considering power washing. The tank (NH3) really isn't all that rusty, but has a couple of old coats of chipping paint & lots of "aged-on" decals here & there. We have a solid 4000 psi & 4 gpm power washer w/interchangable tips. However, would one of the rotary type cutter tips work as a substitute for sand blasting? Or, would it take such a narrow path that it would be a several year job to prep the tank for painting. The tank itself is approximately 48' long by 12' diameter.

Any recommendations? Or, is the water power washer idea a bad one?

Thanks