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Brush Marks in Finish (Read 468 times)
 
Jerry Lear
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Brush Marks in Finish
Oct 28th, 2016 at 10:01am
 
I just finished a cherry platter, sanded to 420 grit, applied Danish oil & let dry.  I then applied three coats of water based poly with a foam brush, letting each coat dry.  After totally dry, I sanded from 500 to 6000 grit.
I noticed that there were brush marks in the finished product.  I was careful not to go over the same areas.
Is there something I am doing wrong?  Is there a way to eliminate or minimize these marks?
Thanks,
Jerry
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Ron Carrabotta
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Re: Brush Marks in Finish
Reply #1 - Oct 28th, 2016 at 10:09am
 
Jerry,
The challenge with water based poly is that it drys so quickly. Whenever I use the water based poly, I use a cheapo airbrush I got from HF,
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does a great job, easy cleanup with water, no brush marks.

If you still have brush marks, I'd go back to 320-400 to get rid of them and then re-apply finish. My $0.02.
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Louie Powell
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Re: Brush Marks in Finish
Reply #2 - Oct 28th, 2016 at 10:42am
 
I have seen pieces finished using a 'rotisserie' method that supposedly minimizes this problem.

The rotisserie method involves applying a fairly thick coat of finish using a brush - while the piece is spinning slowly on the lathe - and then continuing to spin it until the finish can set up.  The continuous rotation, and also slight vibration that accompanies the rotation, will level the finish and minimize brush marks, runs, etc..

The person who recommended this approach uses it for pepper grinders and suggests conventional solvent-based poly since it will take longer to dry, and therefore provides more time for leveling.  I have used it on thin spindles (pens, styluses, etc) with water-based poly.

The key is to have a lathe that can be cranked down to a fairly low speed.  I suspect that if the speed is too high, there would still be leveling, but centrifugal force would cause the finish to the thicker on the outer perimeter of the piece, especially if the piece is something like a bowl or platter.
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Louie
 
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Ron Carrabotta
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Re: Brush Marks in Finish
Reply #3 - Oct 28th, 2016 at 12:12pm
 
Louie,

The method you describe above works very well with regular poly or any of the solvent based finishes.
It will not work on larger pieces using water based poly, as I mentioned, water poly dries too fast.
I have used the "slow turn " method on pieces as large a 10" in diameter on my 3520B turning at 50rpm. Anything larger than that tends to "sling" the finish off of the piece.
I have a designated "slow turner" that rotates at about 15rpm for larger pieces.
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David Mueller
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Re: Brush Marks in Finish
Reply #4 - Nov 10th, 2016 at 6:26pm
 
I agree with Ron. I use General Finishes High Performance polyurethane for all my finishes. It dries fast and hard. I apply it with a fine 3/4" wide artist brush, which produces fewer ridges (easy to clean too). Just put a couple of coats on, sanding between with the highest grit Abranet sandpaper that removes the ridges (usually 400 or 600) and produces a uniform frosty finish. On the final coat, sand with progressively higher grits until you get the surface you want. I finish by burnishing with a piece of brown paper bag and then buff with white diamond to a high gloss, but that's just me.
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Chris Neilan
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Re: Brush Marks in Finish
Reply #5 - Nov 10th, 2016 at 7:53pm
 
I don't ever get brush marks. I never use a brush. I apply poly (and most other finishes) with a clean rag, preferably cheesecloth. I also never turn the lathe on with that rag in my hand! My shop teacher in high school provided me with that tip.  I really wish that high schools  would go back and offer shop classes. That is a rant for another day...
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Ed Weber
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Re: Brush Marks in Finish
Reply #6 - Nov 10th, 2016 at 9:42pm
 
IMO
Brushes are for flat surfaces.
Turned items should be finished with wipe-on or spray.
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Donald Jordan
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Re: Brush Marks in Finish
Reply #7 - Jan 3rd, 2017 at 2:19pm
 
Ron,
I wanted to take minute and thank you for this tip

Ron Carrabotta wrote on Oct 28th, 2016 at 10:09am:
Jerry,
The challenge with water based poly is that it drys so quickly. Whenever I use the water based poly, I use a cheapo airbrush I got from HF,
Multimedia File Viewing and Clickable Links are available for Registered Members only!!  You need to Login or Register.

does a great job, easy cleanup with water, no brush marks.
.....


I've had issues with the water based poly as well, and thought for the little bit of money, I 'd try your suggestion.

I've got to say, I have had great success with this application of poly!! No more streaks or bubbles!!
Thank you very much.
(My wife thanks you as well, as she is tired of hearing me complain about my finishes!!)
Cheesy Cheesy
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Ron Carrabotta
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Re: Brush Marks in Finish
Reply #8 - Jan 3rd, 2017 at 4:26pm
 
Don,

You are quite welcome. Happy New Year!
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