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Polishing base coat before clear?


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So I'm getting ready to try my first really slick, polished paint job and have assembled all the primers, paints and clear coat.

My question is, after I do the final wet sanding of the base coat before the clear coat, should I polish it? Will that interfere with the clear coat adhesion?

Even if final base coat is sanded with 2500 grit, will the very fine sanding lines show through clear coat, or not?

Thanks!

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Definitely do not polish! Unless you want adhesion problems. Paint needs the fine scratches to stick. The 2500 grit you're using is almost too fine. I sand my primer and color coats with 1000 grit. I'll spray two coats of clear, allow it to dry, sand with 2000 and spray a final coat of clear. Then polish.

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I also wouldn't use any type of polishing compound before spraying a clear coat. I know some of the polishes say it will not interfere, but after all of the other efforts to achieve the perfect finish why take the chance? The only thing I might add would be if working with some heavy metallic colors. Depending on how the metallic in the paint it may be an idea to give the finish one last smooth coat of color. As long as it dries smooth, and level then go to your clear and you should still have little or no surface problems before the final polishing.  

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27 minutes ago, espo said:

I also wouldn't use any type of polishing compound before spraying a clear coat. I know some of the polishes say it will not interfere, but after all of the other efforts to achieve the perfect finish why take the chance? The only thing I might add would be if working with some heavy metallic colors. Depending on how the metallic in the paint it may be an idea to give the finish one last smooth coat of color. As long as it dries smooth, and level then go to your clear and you should still have little or no surface problems before the final polishing.  

Yes indeed, I have had issues when I have used polish's and then had to repaint 

 

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Great responses...I totally appreciate them!

I bought some leveling thinner, so hopefully the base coats will go on relatively smooth. It's a metallic Emerald Green, but fine metallic and not chunky style. Just gotta work on my airbrush technique on some scrap plastic so I don't mess this up!

 

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I don't sand metallics before clear coat fwiw. It can cause blotchy looking areas even change the tone of the base color. I've never had a problem with the clear coat peeling etc.. I have sanded the base color then shot another coat of base to even it up though. Kinda depends what paints you're working with too.

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NEVER polish before clear coat, no matter what kind of paint you use..Scuff with 1500 or 2000 then clear..Polish and wetsand the clear..be careful if you sand a metallic..Like someone says before it might show blotches or un eveness..

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Do not wet sand any metallic, pearl, nor base coat for translucent / candy colours ( silver, gold, brass, copper, etc.) . 

Likewise; paint all part which are to be body colour at one time. Metallics --in this instance-- need consistent coats, otherwise an uneven shade / depth may result. 

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Thank you both for the insight. What a deep well of knowledge here! Looks like I'll just lay on the base metallic as smooth as I can and not sand/polish until the clear coat.

Can't wait to get cracking on this. Shipping of the kit is tectonic-slow, so I'll have to be patient.

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Thanks for that, Jim. I like to see both sides of the equation. My feeling is if I can get it smooth enough with a finely sanded primer coat and leveler-thinned base coat, I'll just go ahead and shoot the clear. I appreciate the video.

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On 1/11/2022 at 1:15 PM, rightrudder said:

Thanks for that, Jim. I like to see both sides of the equation. My feeling is if I can get it smooth enough with a finely sanded primer coat and leveler-thinned base coat, I'll just go ahead and shoot the clear. I appreciate the video.

I tend to do the same - if the 'sins' in the color coat are pretty minor I'll use the clear to hide them as best I can. 

I definitely would try sanding any metallics before trying to clear-coat over some cat hair or dirt just because "you can't sand metallics"...in fact I HAVE and DO - just need to recoat to cover up any burn-thru and get it all nice and even again.  

There's very little that you CAN'T fix with paint with some careful sanding and touching-in where necessary, in my experience...

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15 minutes ago, CabDriver said:

I tend to do the same - if the 'sins' in the color coat are pretty minor I'll use the clear to hide them as best I can. 

I definitely would try sanding any metallics before trying to clear-coat over some cat hair or dirt just because "you can't sand metallics"...in fact I HAVE and DO - just need to recoat to cover up any burn-thru and get it all nice and even again.  

There's very little that you CAN'T fix with paint with some careful sanding and touching-in where necessary, in my experience...

I've done the same with hok lime pearl. It was chipped down to the resin (dropped a clamp on it, doh) so some careful prime, base, pearl and clear and you would only see it if you knew where it was.

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Thanks, guys.

CabDriver, I do have a cat, so chances of hair (or entire hairball!) ending up in the paint are high! I'll change clothes before I spray to minimize the risk.

One more question. Once the body shell is sanded and prepped, assuming there is no spot putty used to fill imperfections, is it OK to spray lacquer directly on plastic and skip the primer step? I read another thread that dealt with enamels, and the author chose not to prime because he didn't want to add another layer of paint that might obscure some fine details. 

I want to do what's safe!

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No don't sand the coat before clear.  However, do sand the coat before your last wet base coat. This gives you a deeper finish and if you are using metallic, lets the flakes settle on a smoother surface and look as finely grained as possible.

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On 1/10/2022 at 7:47 AM, rightrudder said:

Great responses...I totally appreciate them!

I bought some leveling thinner, so hopefully the base coats will go on relatively smooth. It's a metallic Emerald Green, but fine metallic and not chunky style. Just gotta work on my airbrush technique on some scrap plastic so I don't mess this up!

 

You picked one of the most difficult types of paints to get an even glossy finish on.   Spray your color coat in very fine layers.  Think of the metal flake like sand in water where the water is the clear tinted color.  As you spray in on, the flake will sink to the bottom of the paint.  If you put down multiple layers each lower layer will stop the flake from sinking any further giving your paint some depth.  To get an even flake lots of fine layers.

Next, sand carefully!  If you get into the flake, you have ruined the paint job and respraying it won't fix it.  Just enough sanding to get a consistently  even top layer.  Use the finest papers you can to get to a level surface and then finish off with a super fine grit and clear.  Put enough clear on so you can sand and polish the clear.  

  One other thought.  Some flakes(like Tamiya micas) get really weird in the panel lines.  The best choice is to clear coat over the panel lines to limit how far the flake can settle in the groves.  Once you clear coat the base then sand it down to the surface plastic and spray your flake over that.  

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Thanks, Pete. Your description does help me visualize what's going on with metallics. I've been rethinking the paints I want to use, given my skill level. Using an airbrush, I'm most familiar with Tamiya acrylics and am leaning toward using them on the body. I've been experimenting on a practice kit (1/16th '57 T-Bird) that I destroyed, but it's really helpful to use the parts to try out different techniques.

The acrylics go on super smooth! Here's Tamiya Metallic Blue (X-13) thinned with rubbing alcohol, sprayed over bare plastic, then wet sanded with 1500 grit and polished with Meguiar's Ultimate polish. I think it would look amazing with a polished clear coat on top...and I do realize that I wouldn't polish the base coat before applying clear; I was just messing around here.

I think this blue would really do justice to the '62 Bullet Bird project (kit should arrive Sunday), with maybe a lighter blue & silver interior.

 

 

 

 

 

IMG_6248.jpg

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5 hours ago, rightrudder said:

Thanks, Pete. Your description does help me visualize what's going on with metallics. I've been rethinking the paints I want to use, given my skill level. Using an airbrush, I'm most familiar with Tamiya acrylics and am leaning toward using them on the body. I've been experimenting on a practice kit (1/16th '57 T-Bird) that I destroyed, but it's really helpful to use the parts to try out different techniques.

The acrylics go on super smooth! Here's Tamiya Metallic Blue (X-13) thinned with rubbing alcohol, sprayed over bare plastic, then wet sanded with 1500 grit and polished with Meguiar's Ultimate polish. I think it would look amazing with a polished clear coat on top...and I do realize that I wouldn't polish the base coat before applying clear; I was just messing around here.

I think this blue would really do justice to the '62 Bullet Bird project (kit should arrive Sunday), with maybe a lighter blue & silver interior.

 

 

 

 

 

IMG_6248.jpg

You should ditch the rubbing alcohol and get some mr hobby leveling thinner.  https://spraygunner.com/gsi-creos-mr-color-leveling-thinner/?sku=T108&gclid=Cj0KCQiAuP-OBhDqARIsAD4XHpf9mUZVLEco-G7H5ziXyf6gBHGJodkjyuQHTojDbsQ5mWD-jBPT0Y4aApQdEALw_wcB

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