and I'm not talking oil canning, there is none of that, the panel is large and when you apply firm pressure to block filler it 'gives' a little. I'm thinking it wont come out straight. Do I just sand it lighter and take alot longer?
Just like slddnmatt says, and in the past, if you can, I have put sound deadener panels in place. They can add a little more "stiffness" to make life easier.
what Matt said..Also, be sure to keep using sharp sandpaper so that it 'cuts' the surface down without you needing to lean into it. what grit paper are you using?
Glue something inert and large underneath - thin - to add support and clears lining but only if lining is removed. Plastic maybe.
That problem affects many modern cars; you'd swear the panels arent much thicker than beer cans. Light touch, start with a coarser grit than you normally would, keep fresh paper on the block, switch to lighter grades as you approach "flat", switch to an easier to sand filler. I like Evercoat Quantum.
The qtrs. on my avatar are 105 '' long and were unsupported we had the same problem.I glued cedar 1x stock in. I used a lock tite shower panel glue,they sure helped. Jack
Used to have this problem, one cure is to stick a piece of styrofoam inside between the inner and outer panel.
I'm using 80 grit but I'm gonna go down to 40 grit on a 17" board and give it a whirl. Thanks for the tips! I use Evercoat Lite body filler and Evercoat Metal Glaze Ultra putty. It goes on like smooth icing and sands better than anything that I've ever used. The loooooong sanding boards are $$$$ so I might have to improvise there...
If it's a crowned area, I'd consider a grille brick. The smell can turn some people away, but nothing feathers better, or matches the contour of curved metal better. The real nice part is you don't use a lot of pressure. Good luck.