It depends on the humidity there,but do it as soon as possible.Down here it's immediately.Use a light coat of 1791 wash primer followed by DP40.Use the green DP40 for the best protection.Anywhere you need to to work just scuff the DP and mud right over it.If you need to weld in patches just remove it in that area and reapply after you grind and clean your welds(sandblasting the weld is the best way to clean them).As far as sandblasting the car,be carefull who does it,they can warp the hell out of your sheetmetal.If you can find someone to media blast it with the plastic beads or nutshells would be better.It usually costs more but there's no warpage to straighten out,and I can tell you from experience that it's a royal pain in the ass to staighten out a warped car.You'll invent new cuss words and want to kill the blaster after just doing the hood or roof alone.You can work the metal a little,but basically you have to find the highest spot and mud out from there to make it look presentable.If they warp it really bad,a case of mud will only be a start.Some blasters know how to do sheetmetal so be sure this one does and will guarantee not to warp your panels into a mess.
