Removing 3 coats of Polyurethane off table


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Old 01-03-07, 06:54 PM
W
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Removing 3 coats of Polyurethane off table

I had a friend of a friend refinish a dining room table and ended up with a poor job of 3 coats polyurethane which feels grainy and looks very thick.

Have tried to remove the polyurethane with sand paper, but doesn't seem to be removing very well. I don't want to remove the stain, just polyurethane, which I know, being a novice, will be a job and a half.

Can you advise please about how to use an electric sander, what type sand paper, and what type sander to buy so that I can remove the heavy coats of poly, untouching the stain, and then putting poly back on.

Any advice would be much appreciated.
 
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Old 01-04-07, 03:50 AM
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If the poly was not lightly sanded and cleaned after each coat, it will end up as you describe, not very good looking or feeling. But you may be able to rescue it. Sand lightly with #220 on an orbital sander, or hand sand, always with the grain. When you have everything smoothed to satisfaction, thoroughly clean with thinner, then apply one coat of thinned poly(oil based). When completely dry, rub lightly with 0000 steel wool or a fine Scotchbrite pad. It should come up looking like a fine handrubbed finish.
Attempting to remove all the finish without disturbing the stain is very difficult.
 
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Old 01-04-07, 07:25 AM
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When you want to make the surface totally flat and shiny, you go through a process called rubbing to get there. Bill has gotten you going with that and I think you'll like the results if you follow his instructions.
 
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Old 01-04-07, 08:12 PM
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I don't know what rubbing means. Could you explain a little more?

With the 3 coats of poly, the table top looks quite bad, and we had already started sand papering the poly off, which is terribly hard. We are only on one of the leafs so far, but decided that we needed to get a small sander, as this is going to be a long and hard and tedious job. But, we'll do it.
 
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Old 01-04-07, 11:37 PM
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You don't need to take all the poly off. You just need to level it, that is take it down only until the brush marks, ridges, and dust nibs are gone. Then one properly applied coat will produce a fine smooth appearance.

I use a Ridgid, about $70, random orbit sander. Use 220 discs, as suggested and change the discs frequently. When the discs pick up crud they leave scratches. Sanding requires patience. Just quide the sander with your hand and don't put pressure on it. Let the abrasive disc do the work; don't try to grind with the sander. My sander is a variable speed model and I use only the lower speeds. The surface will dull as you sand so you use your fingers to feel the smoothness of the surface. When it looks and feel smooth you'll be ready to finish it.

I don't do rubbed finishs so I'll let the other guys explain that.
 
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Old 01-05-07, 05:13 AM
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Rubbing is pretty much what you're doing here, just taken a little further with finer grit abrasives.
 
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Old 01-06-07, 01:47 PM
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Ok, what we tried is not working...bought a small sander, and being a novice, went right through to the bare wood on one of the leafs. Thankfully, we have another leaf we can try. Someone suggested to just buy a bit of walnut stain (I think it was walnut) and lightly stain the spot that I messed up. Is that a possibility?

As was suggested, can we just sand (00 steel wool) the top layer of poly to get the bumps out, then put a coat of satin-oil-based poly over all. And, do I sand over the top coat that we put on, or just leave it. Thankfully, with all this practice, we have not yet touched the actual table, yet.

Thank you ever so much for all the help.
 
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Old 01-07-07, 05:15 AM
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I've had decent luck touching up stain that has been sanded off providing the surrounding areas still have a coat of poly/varnish on them. You do need to use the same color/type of stain that was used for the table.

I'd use sandpaper to level out the 'bumps'. Laying flat it is will do a better job of leveling out the high spots. It is better to not worry about sanding it perfect because of the danger of sanding thru the stain. If it still has a few bumps after sanding and repoly, sand again.

You don't have to sand after the final coat of poly but some prefer to go the extra mile to get the hand rubbed finish. I usually don't.
 
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Old 01-07-07, 08:09 AM
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You do need to sand after every coat of poly IF you are applying another coat. When your satisfied, leave it as is, unless you want the rubbed finish. You should only sand to level the high spots and to provide a *rough* surface for the coat of poly to adhere to.

Key: Thin coats of poly, lightly sand, clean up sanding dust, apply another coat, repeat as necessary.
 
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Old 01-07-07, 08:47 AM
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You do need to sand lightly between each coat of poly (like with 220 grit) in order to create a surface to which the next coat will adhere. Poly has a tendency to peel if no sanding is done between coats.
 
 

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