Before i take my car in for fresh paint job i definately need the cracked/peeling paint sanded down. I've seen cars freshly painted that look wavy on large flat panels like say the door. I dont know if its because they had some kind of filler used to shave moldings or poor sanding, but my question is.. If i sand by hand or use a rubber sanding block will my door panels look wavy like that? Whats the best way? I'd like to avoid using filler as the panels are straight without any major dents. Just a few door dings which i dont even care enough to fix.

 

use a long block with 180grit paper(only if you intend to prime the panels after) sand in a long even stroke in a V shape. if you not intend to prime the panels i would suggest useing 320 grit. look up a company called DURA BLOCK they have the nicest sanding blocks aroung IMO that is. good luck

 

ahh didn't think of using a v-stroke. thanks i'll look into those blocks

 

they are the best IMO like i said. if your gonna re paint fix the door dings you will be so much happier in the end

 

man the paint on my roof is peeling and the hood was previously rattle canned. Should i just buy a DA from harbor freight and go at it? i'll stay away from the corners of course.

 

that wavy-ness is from poor body work and/or prep work... your paint does not hide imperfections, it magnifies them.

you stated that you have a large panel to sand... i dont suggest using a hand block... use a long board... use the grit of sand paper that is approriate... like if i was you i wouldnt be using anything rougher then 120 to sand that clear down...

like that guy stated.. sand in a V... but that doesnt mean go up and down in a V though...
i say do more of an X... a crosshatch.... go in one direction across your panel then come back and cross it in the opposite dirrection...

so its something like this.. \\\\\\\\\ then ///////// crossing it
use a guide coat...

 

is the long board you speak of different than a 16" sanding block like the dura blocks notmighty suggested? Man i'd totally be down to shoot this thing my self if i had a garage to do so.

 

i do beleive that is what he is speeking of. dura block also has a 12" block to. *IF* you buy a DA sander thats great just make sure you keep it flat!!!! to no "dig" this will cause a wavy look once your new top coat is applied. as far as peeling paint i wouls personally sand it back to the original finish/color or bare metal using like 180grit. then apply a coat of corrosion primer followed by 2 to 3 coats of regular primer. let that dry real good, i suggest at least 24hrs. then block that down with 320 and follor over with 600grit and water

 

Theres really no reason to take it back to metal unless its had more than a couple of paint jobs and even then the mil thickness should be okay so the new paint wont sag. As far as what they are telling your yes cross hatchet across the panel real well but for this to be effective you need to spray the panel with a good filler primer good ones from dupont or you can go with marhyde which is a little cheaper but still does the job. You want to do this to build up the low areas and then when you wet sand usually with a 220 or 320 grit and make sure your wet sanding because that way your sandpaper last alot longer. I personally just use a 2x2 good peice of wood works good and is alot cheaper than a durablock. Put on a good 3 coats of filler primer and sand away it will take a while but the outcome is totally worth it and the door or whatever your sanding will be nice and straight. If you just try to block the door with the paint you wont get all the waves out you will just sand into the metal and then you will have to prime anyway over the bare metal. Another trick you can do to make sure you have all the waves out it when you think its good take a can of spray paint and lightly dust the panel with it. Then block it again with the sandpaper and any low lying areas that are still there you will be able to see because there will still be spray paint there. If so just spray that area with some more filler primer and sand some more. Otherwise the waves are so small you will never feel them with your hands or visually.Also a DA should only be used by a experienced body man it seems like its faster but your just putting more waves in your paint sanding deeper in some spots than others and causing yourself more work in the long run, a good body shop will hand sand vs. using a DA. Hope this helps some. Like i said it will take a while but a good paint job is all about the prep work the time painting is the easy part.