rule of thumb for bodywork is, yes you should deal with any rust first... obviously a rust area (or dented/damaged areas) is where you'll be taking the most aggressive approach...
now, underside of a hood, sure you can get away with putting a fancy, schmancy paintjob on the exterior, then deal with the underside later... but technically, it's not the right way to do it..
by the book, you wanna bring a whole panel thru certain processes, not doing step 2, 4, 5, 6, paint.. and going back later and doing 1 and 3 at later dates... it's much easier to have an "accident" and damage your nice painted exterior surface with grind sparks, overspray, etc..
thus why you'll see vehicles running around in spot prime.... they've done steps 1 thru 4 in the damaged areas, then later ya go back and do the 5, 6 and 7 final steps later...
grind/mediablast/treat and repair areas.. rust, dents, etc... repair them... get them in primer.... prep surrounding decent areas for primer, paint, etc..
this especially applies to panels that have the underside, edges, etc getting refinished.... thats how a new fender is done in a bodyshop.... put the whole thing in primer off the vehicle... trim it out, which means paint the underside, edges, inside, etc..... put it on the vehicle.... sand exterior areas, that now have paint lapping over the edges from painting the underside, etc... then paint the exterior sheetmetal last...
here's my rig back in the day running around with a trimmed out door on it...
wow, that response was all over the place.......
any questions, just holla... another PM, whatever...
oh, and I dig Molson Ice....
