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keary_lewis0303 Samba Member
Joined: March 18, 2003 Posts: 98 Location: St Petersburg FL
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Posted: Wed Apr 18, 2018 7:21 pm Post subject: Blocking question |
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I sanded my car with 320 grit and paid a shop to spray 2 part urethane primer on it. Apparently they didn't spray it as thick as I'd like it. I started blocking it with 400 and the paint is getting thin quickly but it is smoothing out nicely. I don't want to pay again to primer it. Can I spray this primer on the thin spots? Or can I just paint over the thin areas since I'm painting the car white any way? I'm using guide coat to block.
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marklaken Samba Member
Joined: March 19, 2004 Posts: 2416 Location: fort collins, CO
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Posted: Thu Apr 19, 2018 12:51 pm Post subject: Re: Blocking question |
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One issue with rattle can primers is that they don't seal the substrate from moisture as well as two part urethane and epoxies. It probably isn't a big deal to use rattle can primer if that's all you ahve access to AND you won't be storing the car in a primered condition for very long.
If you aren't storing the car in a primered condition for more than a few days, you can also consider not priming the sand-thru spots and let them get re-primed when the sealer coat is sprayed right before topcoat.
If the areas that are sanded thru need more build to fix surface imperfections, then you will need to apply more primer for sanding. The sealer coat before topcoat is very thin and won't fix any surface issues. _________________ Wish List:
1967 Wesfalia SO-42 Parts Needed: Kitchenette, Cot Poles
'65 rear left beetle fender
15" Bus Wheels in fair condition
Mark Laken
Fort Collins, CO |
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winston the browndog Samba Member
Joined: August 09, 2006 Posts: 49 Location: connecticut
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Posted: Sun May 06, 2018 8:32 am Post subject: Re: Blocking question |
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You should have had them use a high build primer to do the blocking. Usually it takes 2 or 3 coats to get a good flat surface , blocking between each coat. Then use a good 2 part sealer , before you do final paint. |
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vwkirb Samba Member
Joined: January 16, 2007 Posts: 812 Location: Athens, GA
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Posted: Sat May 19, 2018 10:56 am Post subject: Re: Blocking question |
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When you sand through and there is not an obvious reason why, you have found a high spot on the panel. If you find multiple high spots in the same area then likely the area in the middle of them is low.
If you want the car to be very straight, stop immediately when there is a high spot and evaluate.
You should be using a guide coat to block, the guide coat will really reveal the low and high areas. The guide coat sands off the highs first revealing any lows.
If you have a real low low you will sand through to metal around the dent or low, and the guide will still be in the low area! _________________ Andrew Kirby |
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