Yesterday and today I blasted a boat which I thought would take 3-4 hours. It's a 14' light weight boat he only wanted the outside done. This is the kind 2 people can lift and flip over and such not real big or heavy. I didn't know it had 3 layers of paint on it one top coat of gray and a tough red primer and under coat of gray. I used soda not to warp the aluminum but it took for ever. I went though 6 bags in 6 hours today that was with the media turned up as much as I could. Pressure was max 130 with a 5/16 nozzle. Only asked $300 for it so I lost big time on this one. Was the soda the problem maybe I should have used glass which I did on the back of the boat to get bondo out. I burned up 25 gallons of fuel too so in the end I made about $100 for 9 hours of work 3 yesterday and 6 today.