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Old 12-21-2010, 07:57 AM
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Let's talk sandpaper...

One topic that seems to go on without a lot of detail is "what grit for what stage?". Seems like a good time to bring it up.

What is the minimum grit and maximum grit for adhesion versus hiding before:

Epoxy primer: generally 80g is in the docs. You?

Working filler: 36 to start, 180 to finish are common replies. You?

Sealer: ??

Basecoat: I see 200 to 400 mentioned.

This is the most basic of topics, but I've never really seen it addressed and if ignored, can make the difference between a paint job you can manicure your nails with and a job that blows off when you hit passing gear.

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Old 12-21-2010, 08:29 AM
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You don't sand sealer. As for sanding prior to sealer, 400 grit if a solid color, 600 grit if metallic.
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Old 12-21-2010, 09:17 AM
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I've got a problem with the 36 grit for filler. I've been doing bodywork for 22 years and cant remember the last time I even felt a piece of 36. If you have to start out with that, you need to learn how to put your filler on a little better.
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Old 12-21-2010, 09:23 AM
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I generally use 36 to cut through the paint prior to filler and then sand the filler with 80 grit. If I'm using 3M fillers, I hit the filler with 36 grit to remove the crap that gums up 80 grit. Evercoat doesn't seem to require it so I start with 80 grit on Evercoat.
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Old 12-21-2010, 12:57 PM
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I don't sand sealer or basecoat unless I have a run or a big "booger". If it's basecoat, then I reshoot the color. The paint will stick like glue without it.. and you can mess up the color of the basecoats by sanding... especially metallics.

Here is a tip: Muguiars papers cost more... but you don't get that one large rock on each sheet that cuts a nice scratch in the paint.
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Old 12-21-2010, 02:05 PM
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I "knock 'er down" Filler with 80, then quickly change to 180. I don't sand Epoxy with anything rougher than 180.

I see someone brought up Sandpaper brands, and wondered if everyone could also include their preferred Brand of Sandpaper. Hands down I use PSA rolls the most, I've tried 3M (the worst IMO), and Norton, but my favorite brand is Carborundum-
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Old 12-22-2010, 11:20 AM
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Quote:
Originally Posted by 35WINDOW
I "knock 'er down" Filler with 80, then quickly change to 180. I don't sand Epoxy with anything rougher than 180.

I see someone brought up Sandpaper brands, and wondered if everyone could also include their preferred Brand of Sandpaper. Hands down I use PSA rolls the most, I've tried 3M (the worst IMO), and Norton, but my favorite brand is Carborundum-
+1, I don't sand Epoxy with anything rougher than 180 either.
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Old 12-22-2010, 01:46 PM
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Filler I start with 80's and finish with 240's

Primer....if I'm only priming the once I'll use 600's wet or if I'm priming twice I'll go 400's dry,re-prime and then 600's wet

I'm not entirely sure if UK grits are the same as USA
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Old 12-27-2010, 10:51 AM
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OK, good replies.

What do you consider a minimum grit before (good) filler? I'd think 180 is border line but many may argue that. You?

What is the roughest you'd use before basecoat to avoid sand scratches? 400? 600?? Will basecoat even stick to much finer?

How critical do you feel between the difference of chemical bond of basecoat over primer (wet on wet, or within the reshoot window) versus mechanical (primer sanded after setting up) for adhesion?


These are some things I've got a bit of a handle on, but never really see discussed in detail. I'm sure many of us can learn a few pointers here, and maybe even avoid leaving some paint on the road at highway speeds!
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Old 01-05-2011, 07:16 PM
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On my candy job, i was thinking of sanding the clear and giving it 3 more coats of clear for more depth. What grit is recommended? 800? Also was thinking i may need a scotch pad, especially for the tight areas, would the red color be used and would it be helpful? the clear is really tough stuff, so not sure if the scoth bad would even help
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Old 01-06-2011, 01:46 AM
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Quote:
Originally Posted by cyclopsblown34
I generally use 36 to cut through the paint prior to filler and then sand the filler with 80 grit. If I'm using 3M fillers, I hit the filler with 36 grit to remove the crap that gums up 80 grit. Evercoat doesn't seem to require it so I start with 80 grit on Evercoat.
yup,I also use 36 to cut
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Old 01-06-2011, 02:43 AM
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From rough to fine the only grits I keep stocked are used in the same order although most projects start at 80 grit but there are times that call for 36 on a "killer" or 8 inch "mudder da"


http://www.a2zautoforums.com/showpos...84&postcount=6

IE.
36 tough stuff
80 bondo
180 finish putty
320 machine prep
400 blocking for paint
(red scuff pad)
(during a blend grey ultrafine scuff foam pad)
1000 after paint
(grey scuuf pad)
2000 after 1000

Last edited by milo; 01-06-2011 at 02:53 AM.
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Old 01-06-2011, 07:45 AM
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sanpaper brands

Tucson Jay

Can you say a little more about brands of sandpaper? The reason I ask is I just finished up a black bc/cc job. Started color sanding with 800-1200-1500-2000 and finished up with 2500. When I started buffing I noticed some scratches that won't buff out and I don't know where they came from. I use a 'name' brand wet/dry sandpaper my local jobber carries. Could the sandpaper have defects that cause these scratches? Are some brands worse than others?

Ron
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Old 01-06-2011, 08:09 AM
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you probably picked up some grit when you were wet sanding.....especially if you use a bucket
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Old 01-06-2011, 05:53 PM
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Quote:
Originally Posted by gto_ron
Tucson Jay
When I started buffing I noticed some scratches that won't buff out and I don't know where they came from. Ron
I thought that was normal, happens to me all the time.
I figure it's just the coarse paper scratches that I missed.
It's really hard to get them all.
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