Refinish Urethane coating on Wood table. Not smooth enought? foam roller?

We have a large wood dining room table (maple I think, light color). It has been well used in our family with lots of thin scratches. I don't have the time or energy to stip all the varnish off. But I would like to give it a few coats of vanish to revive the glossy look. So I bought some Urethane and did my first experiment on the spare leaf to see how it would look. So I gave good sanding with 320 grit sand paper, in order to get rid of most of the shine that was left. But no were near enough to see bare wood. So then I gave it three thin coat of Uri thane, and a light very fine grit sanding. But for some reason it does not look all that smooth. Anything tips how to make the finish look smoother and not so bumpy. I tried using a brush initially on a small area but that looked worst. thank.
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Hello,
Try thinning out the urethane 20-25%. This should give bubbles a chance to pop and the coat to level more so than without thinning. Also, urethane takes a while to dry compared to lacquer or shellac. You might be looking at trapped dust. Urethane always has to be leveled to achieve a really smooth coat. That means you have to lightly sand between coats as well.
Good Luck.
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Yes, I did lightly sand between coats. Sorry, I mixed up my terminology, since I have both a can of Urethane and Varathane. I was actually using the water based Varathane, can it also be thinned out? with water? or will that help? thanks.
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Sam wrote:

Normally you'd thin a water-based finish with Floetrol if any thinning is necessary.
Use a good brush, and "flow" the finish onto the surface using long smooth strokes, dipping the brush again if you need to, until you reach the end of the table. Go back and *lightly* drag the brush (held vertically) through the strip of finish you just laid down--this is called "tipping off" and will tend to break any little bubbles. Dip the brush again, and start the next strip of finish.
Try doing a google search for "tipping off finish", and there will be some excerpts from books that explain it with pictures.
Chris
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This won't be very easy any way youdo it. The nature of refinishing and especially polyurethane like this will be very hard to get a good result. Varathane is just a brand name. I think it would be best to spray. You could try wiping it on with like 75% thinned oil based poly many thin coats buff sanded between each but still might not come out as smmoth as you want. I think maybe spraying will be your best bet.
I know it will be expensive to do the whole table this way but I would resand the leaf till most of what you did is gone. Start with 220 and work to 400. Then use a spray can. one light coat back and forth from end to end, then a second immediate coat in the other direction to build up to a completly wet surface. let dry for 24 hours, buff sand, and repeat. You might practice on cardboard or scrap wood of a similar size first to get the spraying down.
Also, have a light 6-10 inches above the surface and about 3 feet in front of you so the work is between you and the light so you can get a good glare off the surface and really see how much wet you are getting so you can lay down a complete wet surface.

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Get a rubber sanding block and some 320/400/600 water proof sand paper. Dunk the block w/320 into a bucket of water and hand sand, sand it all until it looks dull, keep dunking the block into the bucket to keep it clean, wipe dry surface when done with link free cloth, allow to dry. You might then wipe it down with a tack cloth. Thin your finish a bit and apply with a clean good finshing brush. Allow to dry, then water sand again maybe with 320 or 400. repeat these steps, gradually moving up to 600 grit. I did this on an old desser and it turned out like glass in 7 coats.
One other thing is make sure that the finish you are using is compatitble with the old finish.
Cheers, Jim
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I don't know if the old varnish is water based or oil. Those that really matter, since it has been sanded down so much? You would think oil or water base would both work. Also, would an oil based varnish give you a smoother look then the water based varnish? tx
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Hello,
As someone else already mentioned, Floetrol can be used to thin waterborne finishes but I would be very careful about how much to add. These waterborne formulations are carefully balanced and pretty touchy.
As long as you have dealt with any contamination problems in the original varnish, you should be okay. I would put down a sealer coat of shellac before applying the waterborne. Do not use a tack rag after sanding since it will contaminate the surface with respect to the waterborne finish.
Waterborne and oil based finishes will be just as smooth when properly applied. You have to work more quickly with waterborne finishes as they dry faster than oil based.
Good Luck.
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I'm not sure, chances are not. I just remember that when I was researching re-finishing that there were some finishes that should not be used over others.

I would guess oil based might be slightly smoother, since I think it takes longer to dry (more time to level out) but how they are applied is more important.
If your interested I could provide you with an E-book on Wood Finishing. I would need your email address.
Cheers, Jim
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sure, snipped-for-privacy@yahoo.com
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OK, I'm uploading it now 11:47PM Sat, it may take a few mintues for you to dl. It's NOT a really big file (147 pages), it's just that I'm using Rapid Share File Sharing as a FREE service. If you pay to use thier service then it upl/dl faster. When it's done I will send you an email with a link in it. The file is a PDF file which is opened with a free Adobe Reader (you probably already have, if not go to www.adobe.com. Let me know if you have any problems.
Cheers, Jim
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Sam wrote:

You've gotten some good advice but the fact of the matter is that it is VERY difficult to get a perfect, brushed on varnish surface on a large object...one always seems to wind up with a dust nib here and there, probably some lap marks too.
That doesn't mean you can't get a perfect finish, just that it requires more steps. For example, one can rub it down with #0000 steel wool. That will make it smooth as silk but dulls the gloss too. When finished, a coat of paste wax like Johnson's will give it a nice glow...a look I find nicer for furniture than in-your-face high gloss. CAUTION: don't use steel wool if you plan to top coat again with waterborne material.
The conventional method for varnish is to use a felt pad with pumice to rub out varnish; that is followed with rottenstone. There are still finer abrasive materials too.
Once the surface is smooth and flat you could use a power buffer (at low speed and with a light touch) and ever finer abrasives to get the look you want. Very fine abrasives for polishing plastic are available lots of places...auto supply stores, hobby shops, etc. One brand is Meguiar's. Grizzly sells them too - the president is into making guitars; in fact, there is (ued to be?) a "how to" section in their catalog..
Here's an article on polishing plastic... http://www.techguys.ca/howto/polish_lenses.html
--

dadiOH
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