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Old 07-18-2018, 04:07 PM   #1
racin69z
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Method for sanding out wavy panels ...after paint

So i bolted my sons previously wrecked bed down and it seemed to have introduced some waves into the bedside below the body line. I'm going to try to sand and buff it to see how it turns out.


I am trying to decide if i should use a 9" block to knock the tops off, or a short 3" or 4" block to blend it all in. Obviously I can't go too deep, so i am afraid the long block will bridge over the lows.

What to you guys think?

Lynn
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Old 07-18-2018, 04:20 PM   #2
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Re: Method for sanding out wavy panels ...after paint

can you get some good pics of how wavy it is? like lay a straight down the panel or something...a short block may just ride the wave you have where a long block will hit the highs and show where it needs worked..

I fought my doors that the sandblaster messed up and got them very close...now none of my lows are over 1/16"...they were nearly 2"....but it took a lot of hammer and dolley and finally I bought a shrinking disc and that worked miracles...im kinda proud of how they turned out considering what I started with..its the biggest body repair ive attempted....a skim coat of filler and its good now...
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Old 07-18-2018, 05:57 PM   #3
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Re: Method for sanding out wavy panels ...after paint

2 inches thats crazy! They did a number on them. I can try and measure. I'm afraid a pic wont hardly show anything. They are so slight that you have to be moving as you look down the bedside to see them.
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Old 07-19-2018, 12:13 AM   #4
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Re: Method for sanding out wavy panels ...after paint

How much clear do you have on?
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Old 07-19-2018, 08:27 AM   #5
racin69z
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Re: Method for sanding out wavy panels ...after paint

I put 3 wet coats of SPI universal clear.
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Old 07-19-2018, 07:39 PM   #6
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Re: Method for sanding out wavy panels ...after paint

There's only one way to find out.
Start with 1500 until you either burn through the clear or make it flat.
If you burn through, then you into high build with 320.
If you still aren't straight when you hit body filler or steel, then it's 180.
If you still aren't straight, you know what the next steps are.
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Old 07-26-2018, 06:12 PM   #7
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Re: Method for sanding out wavy panels ...after paint

Each coat of clear is roughly .001" thick... not enough to block flat to remove waves without going through.
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Old 07-29-2018, 09:06 PM   #8
racin69z
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Re: Method for sanding out wavy panels ...after paint

Yeah, not going to get them all out. The more i look at it the more i think they were there all the time i just missed them.

Its a daily driver, so it will have to work.

Lynn
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Old 07-30-2018, 12:48 AM   #9
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Re: Method for sanding out wavy panels ...after paint

Quote:
Originally Posted by theastronaut View Post
Each coat of clear is roughly .001" thick... not enough to block flat to remove waves without going through.
Where did you get that number? I have done many checks and it is much more than that! In my tests a few coats will get you .020! Todays clear is like primer in filling! Now my brain could be failing me and my math replicating skills (can't remember the terms) aren't that good. But I have checked after three coats of clear having like 12 mils or something like that, just like spraying three coats if high build primer. Not Polyester primer, that will give you about twice that! But urethane primer and urethane clear give you about three or four mils per coat at minimum.

Brian
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Last edited by MARTINSR; 07-30-2018 at 10:29 AM.
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Old 08-03-2018, 11:02 AM   #10
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Re: Method for sanding out wavy panels ...after paint

Quote:
Originally Posted by MARTINSR View Post
Where did you get that number? I have done many checks and it is much more than that! In my tests a few coats will get you .020! Todays clear is like primer in filling! Now my brain could be failing me and my math replicating skills (can't remember the terms) aren't that good. But I have checked after three coats of clear having like 12 mils or something like that, just like spraying three coats if high build primer. Not Polyester primer, that will give you about twice that! But urethane primer and urethane clear give you about three or four mils per coat at minimum.

Brian
I was thinking about factory clear being only about .002" thick... you're right about urethane clear being much thicker.
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Old 08-14-2018, 04:29 PM   #11
racin69z
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Re: Method for sanding out wavy panels ...after paint

The two most noticeable spots are in the same place on both bedsides. I was reading on another forum on an old post, and they mentioned that the places where you start and stop (overlap) on your coats of clear can show up as waves. Has anyone ever delt with that?

Thanks
Lynn
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Old 08-14-2018, 04:33 PM   #12
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Re: Method for sanding out wavy panels ...after paint

That's called "urethane wave". Newer high solids clears are bad about looking wavy even over perfectly straight parts. You need 4-5 coats and cut it hard with 500 grit on a hard block (thin/flexible plexiglass is perfect) to cut the texture and "wave" out. It helps to not spray each coat overly wet.
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