# How Can I Smooth Out Spar Urethane Brush Marks?



## epson (Jul 28, 2010)

Well first off spar urethane is not the right thing to use on indoor furniture because it dries quite slowly and doesn’t dry as hard as the regular polyurethane. It will work but polyurethane is much better for interior applications. Also using a good natural bristle brush would help to minimize brush marks. With this said, you would have to sand lightly with 150 or 180 grit apply another coat and then sand with 220 grit. If sanding is to slow or your paper keeps gumming up you can use a coarser grit until you get rid of the brush marks. Make sure you don’t sand down to the stain and always sand with the direction of the grain.


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## Millertyme (Apr 20, 2010)

i would sand it down, buy a $12 spray gun from harbor freight and spray it. Those guns spray pretty good for the money. 

If not, sand it down, get a good brush and maybe thin it out a bit.


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## elee532 (Aug 2, 2011)

Thank you both for the quick replies! 


It is an external door (well, there is a screen door between this door and the outside, but I think this still technically makes it an external door). Based on that, this was the finish that Sherwin Williams recommeded. 


I did use a natural bristle brush, albeit an inexpensive one. 


I did not thin the urethane. 


So, if I were to sand down the finish, thin the urethane (about how much?), and reapply with a better brush, do you think I will get better results?


Alternatively, is this the kind of spray gun you were recommending?


Thanks!


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## Ron6519 (Mar 28, 2007)

Sand it down until you can't see the brush marks.
Did you sand it between coats?


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## elee532 (Aug 2, 2011)

Only very lightly between coats. I fear now that I didn't sand enought between coats.


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## Broughton (Aug 1, 2011)

The only way to get a factory finish is to spray it, light coats. When I do shelving I will put on up to seven light coats.


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## Ron6519 (Mar 28, 2007)

elee532 said:


> Only very lightly between coats. I fear now that I didn't sand enought between coats.


You can use a foam brush to minimize the brush marks or you can use a pad on the flat areas.


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## elee532 (Aug 2, 2011)

Pardon my ignorance... What do you mean by a pad?


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## TrapperL (Jul 23, 2011)

If you have a palm sander, sand it until it is 100% flat, no brush marks. Use a wipe on poly that will go on EXTREMELY thin. Do not attempt to make it build. It'll come out like glass. Here's the product at Lowes.
http://www.lowes.com/pd_24499-24-40...||p_product_quantity_sold|1&page=4&facetInfo=


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## elee532 (Aug 2, 2011)

TrapperL, can I use that wipe-on poly that you referenced given that this is an outside door? From what I can tell, the wipe-on stuff is indoor only. Thanks for clarifying!


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## Ron6519 (Mar 28, 2007)

elee532 said:


> Pardon my ignorance... What do you mean by a pad?


watch this:
http://www.youtube.com/watch?v=mG0Rs2IiMGk


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## Jessidog (Jun 21, 2011)

Ron6519 said:


> You can use a foam brush to minimize the brush marks or you can use a pad on the flat areas.


I also had problems with brush marks when using polyurethane, even with a quality brush. I now also use a foam brush and light sanding between coats. I'm much happier with the results.

David


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