How can you sand base coat?

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CedarZ4

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I'm painting a bumper with gloss black paint. I'm using cheap Rust-Oleum Paint + Primer in-one spray I got from Home Depot. Most of it came out ok, but I have some areas that is running. I tried sanding those areas down and now its hazy and no longer gloss finish.

I tried using rubbing compound (like you would with clear coat) to no avail. How do you sand/smoothen gloss base paint and keep it glossy? Is this even possible or must the base coat just be sprayed perfectly.
 
If it's normal rust oleum enamel you can cut and buff it like any other paint. It is not really a base coat since it does not need to be cleared, but can be.
The issue is the paint it typically very soft and oxidizes quickly. If your sanding and buffing make sure to get enough paint on it. I have painted a couple motorcycle tanks with spray rust oleum paint and clear with great results.
 
What grit sanding paper are you finishing with, and compound are you using?

Sand to at least 1500 grit wet, 2000 would be better, if you have an aggressive compound and machine to polish with. Maybe go up 3000 if you want to ease the cut and polish step if you are doing it by hand.
 
This was a project I started last year that I am attempting to redo, so I don't remember what grit I went up to exactly. But I started with 200 and went up. I hadn't thought about trying to use compound on it until a few days ago, and I used Ultimate Compound by hand since I didn't have any spare pads to use with the DA. So if I am understanding correctly, as long as I use a gloss-black paint and wet-send up to 2000 and then hit it with some compound, it should buff back to gloss finish?

Is there a difference between enamel vs. lacquer or any other spray paint? This was the one I used: Rust-Oleum Universal 12 oz. All Surface Gloss Black Spray Paint and Primer in One-261402 - The Home Depot
Any recommendations on what paint would polish well to obtain a gloss black finish?
 
If the results are glossy after it dries then you should be able to sand and buff and end up with glossy paint.

I don't know anything about this specific paint with a built-in primer? Perhaps contact the company and ask if it can be sanded and buffed to a glossy finish?

Also important is having plenty of paint. I've never started as low as #200 grit. That's too aggressive in my book for this type of work.

I'd start at #1500 to knock down the peel and then finish out with #2000 and higher like the Trizact #5000 by machine (if possible).


M105 works great by hand. It was the first compound I know of that actually did work at all by hand. I did the below using M105 for the pictures. I machine compounded the rest of the car and you can read the entire write-up for this El Camino here,


Damp-Sanding Tools, Tips and Techniques by Mike Phillips

RemvovingSandingMarksbyHand01.jpg


RemvovingSandingMarksbyHand02.jpg


The above pictures taken from my article here,

The Rule of Thumb






:)
 
Hey Mike, I think he went aggressive trying to get rid of paint runs. But I agree, that's way too aggressive for paint.

Mike had an article about removing runs on the hood/front fender of his big red truck with sanding blocks, but I can't seem to locate it. I promise it didn't start with 200 grit.
 
CedarZ4 said:
Is there a difference between enamel vs. lacquer or any other spray paint?

Any recommendations on what paint would polish well to obtain a gloss black finish
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Since you've already shot the panel with a low quality paint I'd shoot it in an automotive type acrylic enamel only. If you try to use a more volatile paint system like a base/clear you're gonna have some lifting of the previous finish (unless stripped prior to refinishing). Your local body paint supplier (jobber) can mix some ready to spray acrylic enamel in a spray can that's ready to shoot. Or you can order online from different company's that do the same thing.

APS Tower Paint Company, Inc.

The main difference between enamel & lacquer is...

You can shoot enamel over any properly prepared finish. With lacquer you can only shoot over previous lacquer painted surfaces including lacquer based primers/sealers. Back in the day lacquer paint was used for spot repairs, it was possible to shoot over factory baked OEM enamels because it was harder for the solvents (lacquer thinner) to lift the tough baked on finish.

Lacquer over enamel :mad:

lifting_topview_L.jpg
 
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Thanks for the response everyone, they've been really informative. I gave Rust-Oleum a call and it looks like most of their spraycans are sand and buff-able back to original finish, including the paint+primer in one. I ended up wet-sanding an area with 1,500 and hit it with the DA and sure enough, it got the gloss finish back.

In regards to the 200grit. I didn't mention that there were some cracks on the panel that I had to patch up. I used the 200grit initially to sand the imperfection after patching, and ended up using it to sand the whole panel was well. I will search for Mike's post on removing runs and start with a finer grit this time around.

RedXRay - Would something like this work? Rust-Oleum Automotive 12 oz. Black Gloss Acrylic Enamel Spray Paint-248643 - The Home Depot
Considering how I'm a very beginner level painter, I'd rather waste a $6 can of paint rather than a $20+. If I'm not looking for any specific color, just "gloss black" is there a quality difference between your run of the mill Home Depot Rustoleum, or something like the APS you linked to?
 
CedarZ4 said:
RedXRay - Would something like this work? Rust-Oleum Automotive 12 oz. Black Gloss Acrylic Enamel Spray Paint-248643 - The Home Depot
Considering how I'm a very beginner level painter, I'd rather waste a $6 can of paint rather than a $20+. If I'm not looking for any specific color, just "gloss black" is there a quality difference between your run of the mill Home Depot Rustoleum, or something like the APS you linked to?
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It really boils down to the quality of finish you're looking for. Rustoleum is a good general product for what it dose. The automotive finishes that a body supplier puts in an aerosol can are exactly the same products used in the industry such as DuPont, PPG, R-M, Glasurit etc.

True these products cost a heck of a lot more but they have higher quality pigments (color) that stand up to the weather/sun, better adhesion and flexibility, correct hardness to resist chipping and not to soft that marring will be an issue during the polishing steps. On a bumper, especially the front with rocks, sand and bugs hammering at the finish at 55mph+...

Bottom line it's a judgment call on the condition of the rest of the vehicles finish. If the product you used got the job done satisfactory that's all that counts!
 
Even for a beginner you will probably get better results with duplicolor base coat and clear or maybe even Eastwood y2k spray can clear with hardner.
 
MPBGT said:
Even for a beginner you will probably get better results with duplicolor base coat and clear or maybe even Eastwood y2k spray can clear with hardner.
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I'd agree... before the Rustolum was applied. I'd be afraid of it lifting with a base/clear system. Those chemicals are pretty hot especially those spray can systems that introduce the catalyst while spraying.

The product he'll be shooting over is an oil based product. Not sure how a solvent based system might react over that type of paint.

Rustolum said:
Oil based formula covers up to 35 sq. ft. protects surfaces from rust and dries to the touch in as little as 30 minutes.
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CedarZ4 said:
Thanks for the response everyone, they've been really informative.
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AGO = Good forum. Share with your friends. Win/Win.


CedarZ4 said:
I gave Rust-Oleum a call and it looks like most of their spraycans are sand and buff-able back to original finish, including the paint+primer in one.

I ended up wet-sanding an area with 1,500 and hit it with the DA and sure enough, it got the gloss finish back.
Click to expand...


Good to hear. Better yet is how many people a thread like this will help into the future.


:xyxthumbs:
 
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