Sanding/Polishing Polyurethane to a Mirror Finish - Page 1

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[ARCHIVED THREAD] - Sanding/Polishing Polyurethane to a Mirror Finish

Posted: 3/16/2017 4:16:21 PM EDT

Any specific ways to do this. I`m spraying three thin coats on a project and it needs to shine!

Posted: 3/16/2017 4:22:38 PM EDT

[#1]

It needs to be fully cured. I wouldn't touch it for a couple weeks, if we are talking about a product made for wood finish. Then it would be like polishing a fresh car finish. A variable speed buffer and various automotive polish products from Meguiars would get it done.

I stopped using gloss. I only use satin and I think the results are much better.

Car finishes are a different animal. The P-sheet for the product will tell you dry time. Then you can see the polishing process on the youtoobs.

Posted: 3/16/2017 4:45:48 PM EDT

[#2]

My neighbor (painter) used to clear coat his cars, and he'd be wet-block sanding the orange peel out of them 24 hours after spraying. (or less)

What is the base material and color?

Posted: 3/16/2017 5:12:27 PM EDT

[#3]

Thanks guys for the quick response. It`s a Giant Scale RC Plane. Primer over fiberglass followed by latex paint sanded to 1000-1200 grit before i put the Polyurethane on. This step is where I need your help.

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Posted: 3/16/2017 5:23:20 PM EDT

[#4]

I didn't even know you could apply poly over latex.

Posted: 3/16/2017 5:33:12 PM EDT

[#5]

Quote History

Quoted:
I didn't even know you could apply poly over latex.

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I was thinking the same thing. OP, you might want to do a test run first.

Posted: 3/16/2017 5:40:32 PM EDT

[#6]

I will. I`ve been assured that I can.

Back to the shiny issue.

Posted: 3/16/2017 6:10:04 PM EDT

[#7]

Quote History

Quoted:
I didn't even know you could apply poly over latex. <img src="http://www.ar15.com/images/smilies/smiley_abused.gif" />

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They make water based polyurethane, so I can see that it is possible. You will want to wet sand with 600 grit and then 1000 grit before hitting it with Dupont rubbing compound, and then a fine grit of liquid polish. That can easily be done by hand. Meguiars will make it like a mirror.

Posted: 3/16/2017 10:42:32 PM EDT

[#8]

Spraying the finish is a great start, that will give you a better finish to start off with. Here are some more tips for you:

http://www.woodworkersjournal.com/rubbing-great-finish-satin-gloss/

Posted: 3/17/2017 11:53:27 AM EDT

[#9]

The problem that shows up with poly is that the layers are on each other.

Faint 'witness lines' can show if you rub through the top layer to the next one.

Varnish has the same issue.

Lacquer and shellac melt together so no witness lines.

If the lower coats are not completely cured before adding another coat you can 'crinkle' the new coat.
The only cure is complete removal and start over.

And it is a real PITA to remove until it HAS cured all the way though.

Posted: 4/10/2017 1:18:20 PM EDT

[#10]

The water based poly did the trick!!!!

I`m very happy with the results The poly was "milky" at first but dried/cured to a beautiful finish I`m sure the parts of the plane remaining after I crash it will still be shiny,

Posted: 4/10/2017 1:58:40 PM EDT

[#11]

Quote History

Quoted:
I didn't even know you could apply poly over latex.

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Before Sherwin Williams came out with their latex acrylic Pro Classic trim paint, a lot of people would mix latex paint and oil based polyurethane in about a 50/50 ratio. It would give you the look and feel of an oil based paint, without the yellowing as years pass.

Posted: 4/10/2017 2:08:27 PM EDT

[#12]

Sand first with 800 wet to knock down the orange peel. Sand second with 1500 wet, than 2500 wet. Buff to brilliance.

[ARCHIVED THREAD] - Sanding/Polishing Polyurethane to a Mirror Finish

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