keep sanding through same high spots

[Mikec35]

I blocked my epoxy primed front fender and sanded through 3 or 4 high spots. Sprayed 3-4 coats of polysurfacer and blocked again, sanded back through the same spots again. They are about 1-2 inches in size. Not sure what to do. Its the top of a 67 mustang driver's side fender. I think maybe my durablocks may be too rigid for the contour? Should I add another 3 or so coats of polysurfacer and try a less rigid block? Should I just spot prime or spray the whole top of the fender? Also, I have been using a 3m no. 20 sanding sponge on the really contoured areas of the fender, is this ok? Thanks for any advice.

[Len]

You want to use the stiffer block and sand at an angle around the along the shape of the panel. Use guide coat when you sand so that you see exactly what you're doing. Don't use the sponge because it's not leveling the surface it's just removing material.

The concept you want to remember is that you are removing the material over the high spots and leaving the material in the low spots. Don't try to remove any material in the low area until it's level with the high area.

I know it can be frustrating until you get the feel for what you're doing but take your time and use a coarse grit like 180 to do the initial leveling of the surfacer because it will tend to cut it level instead of following the surface irregularities. Take your time and always use a light dusting of Guide Coat.

Dry Guide Coat for Dry Sanding - Link


Aerosol Guide Coat for Wet Sanding - Link

[Mikec35]

Len, thanks for the reply. I actually used durablocks on most of the fender, just used the sponge on a few tight, curved areas near the edges. I used sikkens spot primer in a spray can as a guide coat, I may have put too much of it on as it is tough to come off with 180 grit paper. I'll spray more polysurfacer and hopefully build up the surface around the high spots and try to level it off again.

[pane2k]

if the spots are that low you may want to consider putting a thin skin of polyester putty over the low spots.. block sand it even then reprime.

[Chris L]

Another thing is to make sure you sand in an x pattern..to help elimate the low spots without cutting flat spots.