Paint sanding question

[dodgemahal]

I'm not sure if I'm in the right sub-forum, but here goes:

I haven't prepped a ride for painting in a few years so I forgot something. How do you keep from cutting through an edge while sanding a fresh coat of paint? By edge I mean something like a character line that runs the length of the vehicle. My 73 Dart has several of those. If I'm not careful it's easy to sand down to bare metal.along that "peak". I think there's a technique but don't remember what it is. Thanks.

 

[Oldmanmopar]

Use a sanding block or board and only sand the flat surfaces and never cross the body lines, After this is done you can go over the body lines lightly by hand to scratch these areas for adhesion for more paint or go straight to buffing . You can run a piece of tape on the lines to make or keep them straight. But never cross the lines while sanding.

 

[1MeanA]

Why are you sanding a fresh coat of paint? Are you doing a cut and polish on a base/clear paint job?

 

[dodgemahal]

Good info Oldman! I use blocks but I probably should switch to a hard board near those lines. Thanks.

To onemeanA: I'm going to shoot with an initial coat of epoxy. I always sand that with 400 grit, then apply a skim coat of filler where I need it, then more epoxy and sand once again. I know we all go about it differently but that's how I do it.

 

[1MeanA]

Typically filler needs a coarser grit under it. After epoxy most people spray a 2k primer or high build primer which is much easier to sand than epoxy. Block it 180, reprime and then sand 320/400 then 600 depending on whether your going to paint or sealer.

 

[dodgemahal]

Typically filler needs a coarser grit under it. After epoxy most people spray a 2k primer or high build primer which is much easier to sand than epoxy. Block it 180, reprime and then sand 320/400 then 600 depending on whether your going to paint or sealer.

Thanks for the advice. I'll try that. I'm still learning.

 

[1MeanA]

There are lots of good resources out there…YouTube, forums, FB, etc. of course you have to figure out the knowledgeable people. I go to autobody101.com , spiuserforum and a few YT channels like Paint Society

 

[harrisonm]

Typically filler needs a coarser grit under it. After epoxy most people spray a 2k primer or high build primer which is much easier to sand than epoxy. Block it 180, reprime and then sand 320/400 then 600 depending on whether your going to paint or sealer.

TOTALLY what he said. You will regret sanding with 400 and then applying filler. 400 will not give the 'tooth' required to give the filler something to really stick to.

 

[dodgemahal]

TOTALLY what he said. You will regret sanding with 400 and then applying filler. 400 will not give the 'tooth' required to give the filler something to really stick to.

I guess I've been lucky then......no problems with past projects, but I will heed your advice. It makes sense and you guys know better. Thanks.

 

[dodgemahal]

Getting back to the original reason for this thread, here's what i was talking about.

 

[1MeanA]

Why are you sanding a fresh coat of paint? Are you doing a cut and polish on a base/clear paint job?

Getting back to my question...why are you sanding paint? I see now that you are doing a 'scuff and shoot' meaning you are going over the old paint. Of course the whole job is as good as what is underneath it. In this case I would clean and sand 320....enough to rough it up. For areas needing repair you will need to sand 80 grit in the area to hold the filler. You can then sand and feather the filler working your way from a coarse grit to 320. I would think a primer/sealer over top would be required before thinking of painting. You should see how good your repairs are after this. Blocking the repaired areas will show you the problems. At least that is what I would do. I don't want to come across as a pro because I am not but I have done a bit of work and a fair amount of research.

 

[dodgemahal]

Getting back to my question...why are you sanding paint? I see now that you are doing a 'scuff and shoot' meaning you are going over the old paint. Of course the whole job is as good as what is underneath it. In this case I would clean and sand 320....enough to rough it up. For areas needing repair you will need to sand 80 grit in the area to hold the filler. You can then sand and feather the filler working your way from a coarse grit to 320. I would think a primer/sealer over top would be required before thinking of painting. You should see how good your repairs are after this. Blocking the repaired areas will show you the problems. At least that is what I would do. I don't want to come across as a pro because I am not but I have done a bit of work and a fair amount of research.

I think you are correct, and I thank you for your write-up.

 

[hcallaway]

I used a 80 grit to get the damaged areas down to bare metal.(120 to cut filler when I do the bodywork) Then the 180 to feather imperfections.

180 grit 24 hours sanding with a orbital sander.

I gave it to the shop after the 180.

High Build Primer after the shop did the body work.
I got it back and then 320 grit 16 hours sanding.
Blocking each flat panel.
Do not hit the body lines to make them crisp.

Last picture shows it after I gave it to the body shop. They sprayed down a black guide on all the body lines to do the initial bodywork to make sure they kept the lines.

Now it is time to go back to the shop for paint.

 

[WAYNE0]

T

I'm not sure if I'm in the right sub-forum, but here goes:

I haven't prepped a ride for painting in a few years so I forgot something. How do you keep from cutting through an edge while sanding a fresh coat of paint? By edge I mean something like a character line that runs the length of the vehicle. My 73 Dart has several of those. If I'm not careful it's easy to sand down to bare metal.along that "peak". I think there's a technique but don't remember what it is. Thanks.

ape the top edge of a body line block sand it. Then with that tape still on run tape up next to it. Take the first tape off then block sand up to that edge. Hope this make sense lol

 

[dodgemahal]

T

ape the top edge of a body line block sand it. Then with that tape still on run tape up next to it. Take the first tape off then block sand up to that edge. Hope this make sense lol

Wow. That makes perfect sense. I had thought about something like that but wasn't sure if it would work. Glad you let me know....thanks!