my stupid sis backed into my bumper and i gotta get it repainted im goin to sand it myself.. what gritt should i start off with and what should i end of with and sand just to the black right ?

 

did it spider crack the paint?? did it leave damage??? If not then 400-600-800

 

I would bust out the d/a if it spidered on you, but i dont think you would have that off hand. I would use something coarse like 80grt to get down to it with the d/a even by hand then 400, 600.

 

give usmore details on the damge . as far as grit ilike tostay fine so 600+ would be good .

 

yea all spidercracks deff have to sand down the hole thing

 

bump!!!!!!!!!

 

I'm a wuss when it comes to sanding urethane, 80 grit's pretty danged aggressive on a DA. I'd use 180, take it down to where the spidercracks are gone.

 

I use 180 for spider cracks and then come back with 400 and some superfine around the edges. Sand until it looks like the orange peel is going away. A d/a will turn this into a 10 min job.

 

going from 180 to 400 will not get the sanding marks out...always go to next size until you reach the desired level...220-320-400...etc..

 

for spidering use 150 on a da or block it by hand, just takes a bit longer, feather around and over all the 150 scratches with 400, then high build prime it sand until smooth, if you still get fuzz coming threw in the plastic reprime it, then to prep for paint you can use 400 to 600 if you want to recolor the whole thing, or use 1000 over the whole bumper to scuff the clear, to reclear the bumper, hope that made sense to you

 

im goin to sand it tomorrow i have a d/a so bacially i sand all the spidercracks down to the black with 150 feather around it then use 400 and scuff the rest of it??????????

 

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I would reprime the whole thing with epoxy primer after sanding (your 150/400 should be fine), let that set up, sand the epoxy with 600 wet, and then shoot. The epoxy will seal everything below it.

I must retract my earlier statement about 80 grit though. I started sanding on my Fiero this weekend, and started with 180 on the DA. After going through 2 discs in about 3 square feet (the Mirka gold paper was loading up), I switched to 80 grit. I was able to do most of the rest of the bumper with 1 sheet of 80. Yeah, I am being VERY careful around any molded transitions (points, ridges, etc), because they'd be very easy to burn off. But for the 5 layers that I have to sand through (original silver paint, gray build primer, green sealer, silver paint, dark silver paint), the 80 grit was the only way to fly.

150 will work fine for a smaller (1 sq ft) area though.

After I knock all this junk off, I'm going back with a coat of epoxy primer, wet sanding that with 600, and then spraying the base (Viper Blue) and clear.

 

I HOPE YOU MENT TO PRIME THE WHOLE AREA HE WORKS, NOT THE WHOLE BUMPER IT WOULD BE A WASTED OF TIME AND PRIMER TO PRIME THE WHOLE COVER

 

If its not to late I would suggest 220 on a da until the spider cracks are gone or very faint. Then progress to 320 feathering it out 6 inches beyond the 220 are. Then use 500 on the whole bumper. After that you should get a product called KOMBI putty that is used to fill in small scratches and sand marks. When that has dried use 600 wet and a flexible sanding block to remove the extra putty. Hope this helped