# Rubbing Compound over Polyurethane



## GAF (Nov 4, 2012)

Can I hand apply rubbing compound over the final coat of poly to get the smoothness and feel that I want? I am not looking to rub out the finish. I want to leave it semi-gloss but just make it smoother.

Gary


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## m.n.j.chell (May 12, 2016)

When you say, "Make it smoother," ... what are you trying to smooth out?
If you're referring to anything more than sanding scratches, rubbing compound probably won't do it. Automotive finish rubbing compound is one step away from polishing wax. 
It puts a gloss finish on the surface, but it doesn't really remove much of the finish at all.


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## Steve Neul (Sep 2, 2011)

GAF said:


> Can I hand apply rubbing compound over the final coat of poly to get the smoothness and feel that I want? I am not looking to rub out the finish. I want to leave it semi-gloss but just make it smoother.
> 
> Gary


First of all poly dries very slow. The finish would need to dry a month before using compound or waxes on it. It just needs to cure completely or these foreign substances can get into the finish. 

If the finish is already semi-gloss rubbing compound will turn it into gloss. The way a finish works is there is a flattening compound in the finish that looks like baby powder. When you apply the finish the flattening compound comes to the surface and interrupts the sheen. Then you come along with rubbing compound which should be looked at like a really fine sandpaper and rub the outer layer of the finish off with the flattening compound. What is under it is gloss. The more you rub it the farther you get into the gloss and the shiner it gets. Chemically there isn't any real difference between a gloss poly and a satin poly. The more of this flattening compound that is added makes the difference between gloss and satin. This is why I don't care for rubbed finishes. Depending on how much you rub or how hard makes a difference in how much of the flatting compound is rubbed off. This tends to make the sheen blotchy because some places will get rubbed more than others. 

The best thing I could suggest is wet sand the table with 2000 grit paper and very lightly buff the finish with 0000 steel wool. You put almost no pressure on the wood as that would tend to make it streaked. If the sheen doesn't come back enough after applying a polish you might have to rub it a little with rubbing compound.


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## GAF (Nov 4, 2012)

mikechell said:


> When you say, "Make it smoother," ... what are you trying to smooth out?
> If you're referring to anything more than sanding scratches, rubbing compound probably won't do it. Automotive finish rubbing compound is one step away from polishing wax.
> It puts a gloss finish on the surface, but it doesn't really remove much of the finish at all.


It's final top coat smoothness that I continue to have trouble with. The one thing that I have been doing that has been helping is rubbing with a paper bag.

Gary


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## GAF (Nov 4, 2012)

Steve Neul said:


> First of all poly dries very slow. The finish would need to dry a month before using compound or waxes on it. It just needs to cure completely or these foreign substances can get into the finish.
> 
> If the finish is already semi-gloss rubbing compound will turn it into gloss. The way a finish works is there is a flattening compound in the finish that looks like baby powder. When you apply the finish the flattening compound comes to the surface and interrupts the sheen. Then you come along with rubbing compound which should be looked at like a really fine sandpaper and rub the outer layer of the finish off with the flattening compound. What is under it is gloss. The more you rub it the farther you get into the gloss and the shiner it gets. Chemically there isn't any real difference between a gloss poly and a satin poly. The more of this flattening compound that is added makes the difference between gloss and satin. This is why I don't care for rubbed finishes. Depending on how much you rub or how hard makes a difference in how much of the flatting compound is rubbed off. This tends to make the sheen blotchy because some places will get rubbed more than others.
> 
> The best thing I could suggest is wet sand the table with 2000 grit paper and very lightly buff the finish with 0000 steel wool. You put almost no pressure on the wood as that would tend to make it streaked. If the sheen doesn't come back enough after applying a polish you might have to rub it a little with rubbing compound.


Steve I would be too impatient to wait a month. Wow.

Thanks for the good explanation of the sheen differences. I do learn something new every time we "talk".

I assume that I can use the wet sand approach anytime after the final coat???

Gary


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## Steve Neul (Sep 2, 2011)

GAF said:


> Steve I would be too impatient to wait a month. Wow.
> 
> Thanks for the good explanation of the sheen differences. I do learn something new every time we "talk".
> 
> ...


I would wait a couple days to wet sand. The finish might be a little gummy and if the paper grabs it it can pull up a wad leaving a hole to have to fix. 

Sometime when you have a can of satin going bad before stirring it reach to the bottom with a stick and pull some of the flatting compound off the bottom and let it dry on the stick. It will dry to a clump that looks like plaster. This is why we recommend when finishing to a satin finish you build the thickness of the finish with gloss and use the satin for the final coat. This powder builds up coat after coat reducing the clarity of the finish where a gloss finish has none of this stuff in it.


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## ColorStylist (Jul 19, 2014)

GAF said:


> Can I hand apply rubbing compound over the final coat of poly to get the smoothness and feel that I want? I am not looking to rub out the finish. I want to leave it semi-gloss but just make it smoother.
> 
> Gary


Take a brown paper bag, the kind you would pack your lunch in, and rub over the finish. The brown bag acts like 4000+ grit sand paper and will remove alot of roughness without scratching the finish. Give that a try.

EDIT: I see where you have used a brown bag. That should smooth the finish out pretty good.


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## GAF (Nov 4, 2012)

ColorStylist said:


> Take a brown paper bag, the kind you would pack your lunch in, and rub over the finish. The brown bag acts like 4000+ grit sand paper and will remove alot of roughness without scratching the finish. Give that a try.
> 
> EDIT: I see where you have used a brown bag. That should smooth the finish out pretty good.


Thanks. Yup I do like the paper bag and it does help.

The frustration that I am dealing with is that I used to get very nice smooth finishes a few years ago and then something changed and now i have difficulty much of the time. I have never been able to determine what went wrong or what changed.

Awhile ago Steve mentioned getting away from fast drying poly. I haven't searched much for slower drying poly but I think I should. I always let the poly dry overnight.

Gary


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## ColorStylist (Jul 19, 2014)

The only thing about getting away from fast dry poly is this.....the longer it stays wet, the bigger chance you have on things falling into it.

The key to getting a smooth finish is applying a good enough build over multiple coats and a smooth sanded surface between each coat. Your last coat you need to make sure the surface is free of dust, and apply a thinner coat. Your last sanded coat should be smooth and level.


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## Steve Neul (Sep 2, 2011)

I would imagine when you started refinishing your shop was cleaner. Dust gets airborne so bad it gets everywhere and the least little movement of stuff in your shop while you have wet poly could result in dust blowing into the finish. Personally I don't care for a finish that dries as slow as polyurethane but when ever I used it I wait until I am finished for the day and blow everything off with compressed air and come back in an hour or so and apply the finish. Then it's Elvis has left the building. I get away from it and don't see it until the next morning. It's always important working with any finish to blow yourself off. Most of the time when dust gets into a finish it comes off your clothing.


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## epicfail48 (Mar 27, 2014)

Ive tried polishing poly a few times before, it never ends well. Even fully cured the poly is a little too soft, the polishing compounds never seem to work well in it. Think of trying to use a piece of sandpaper on a rubber eraser. The one thing I've found that works well is to buff my second to last coat with 0000 steel wool or similar, then wipe on a very, get thin coat of poly mixed 50:50 or so with mineral spirits. Do it right and that top coat will fill the tiny scratches left by the wool and dry before anything has a chance to settle in it


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## GAF (Nov 4, 2012)

ColorStylist said:


> The only thing about getting away from fast dry poly is this.....the longer it stays wet, the bigger chance you have on things falling into it.
> 
> The key to getting a smooth finish is applying a good enough build over multiple coats and a smooth sanded surface between each coat. Your last coat you need to make sure the surface is free of dust, and apply a thinner coat. Your last sanded coat should be smooth and level.


My frustration is that I do all those things and still have issues with the very last top coat which is why I use the paper bag approach.

Gary


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## GAF (Nov 4, 2012)

Steve Neul said:


> I would imagine when you started refinishing your shop was cleaner. Dust gets airborne so bad it gets everywhere and the least little movement of stuff in your shop while you have wet poly could result in dust blowing into the finish. Personally I don't care for a finish that dries as slow as polyurethane but when ever I used it I wait until I am finished for the day and blow everything off with compressed air and come back in an hour or so and apply the finish. Then it's Elvis has left the building. I get away from it and don't see it until the next morning. It's always important working with any finish to blow yourself off. Most of the time when dust gets into a finish it comes off your clothing.


Steve there are some truths in what you say. What I have been trying lately is to apply a top coat and then move the piece to a room far away from the workshop. Someday I will get back to where it used to be.

Gary


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## GAF (Nov 4, 2012)

epicfail48 said:


> Ive tried polishing poly a few times before, it never ends well. Even fully cured the poly is a little too soft, the polishing compounds never seem to work well in it. Think of trying to use a piece of sandpaper on a rubber eraser. The one thing I've found that works well is to buff my second to last coat with 0000 steel wool or similar, then wipe on a very, get thin coat of poly mixed 50:50 or so with mineral spirits. Do it right and that top coat will fill the tiny scratches left by the wool and dry before anything has a chance to settle in it


Well timing is good for a test of what you suggest. I am about to put my 6th diluted top coat on a dining room table and I will try your approach. Thanks.

Gary


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## Steve Neul (Sep 2, 2011)

GAF said:


> Steve there are some truths in what you say. What I have been trying lately is to apply a top coat and then move the piece to a room far away from the workshop. Someday I will get back to where it used to be.
> 
> Gary


You can get dirt in the finish just moving the project. It would be better to put down a drop cloth and apply the finish in the other room and then get away from it. This is why so many of us use faster drying finishes. With a finish like lacquer it dries to touch in a few minutes eliminating the need for such a clean environment to work. Myself I'm still finishing outdoors since I had to move my woodshop into my finishing shop. I have to use lacquers.


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## GAF (Nov 4, 2012)

Steve Neul said:


> You can get dirt in the finish just moving the project. It would be better to put down a drop cloth and apply the finish in the other room and then get away from it. This is why so many of us use faster drying finishes. With a finish like lacquer it dries to touch in a few minutes eliminating the need for such a clean environment to work. Myself I'm still finishing outdoors since I had to move my woodshop into my finishing shop. I have to use lacquers.


Good feedback Steve. I have in fact done that with the dining room table top because it is too awkward to move after top coating. I will now start to do the same with the smaller pieces.

Gary


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## GAF (Nov 4, 2012)

ColorStylist said:


> Take a brown paper bag, the kind you would pack your lunch in, and rub over the finish. The brown bag acts like 4000+ grit sand paper and will remove alot of roughness without scratching the finish. Give that a try.
> 
> EDIT: I see where you have used a brown bag. That should smooth the finish out pretty good.


How long do you wait before doing the paper bag rub?

Gary

P.S. Do you mind telling me your first name?


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## ColorStylist (Jul 19, 2014)

GAF said:


> How long do you wait before doing the paper bag rub?
> 
> Gary
> 
> P.S. Do you mind telling me your first name?


What grit are sanding to before applying your last coat? I always block sand with 240 after the 2nd coat. I agree with what Epic said above, and it goes back to what I said earlier as well. Make sure you have a smooth surface before applying your final coat, and thin your final coat. 

I would wait 48 hours before doing the brown paper bag rub. As long as the finish is good and dry, you will be ok.

I went by Randy****1971 before this site had problems, so I just made another username and started over. Im the one that kept trying to get you to spray, LOL


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## Steve Neul (Sep 2, 2011)

ColorStylist said:


> What grit are sanding to before applying your last coat? I always block sand with 240 after the 2nd coat. I agree with what Epic said above, and it goes back to what I said earlier as well. Make sure you have a smooth surface before applying your final coat, and thin your final coat.
> 
> I would wait 48 hours before doing the brown paper bag rub. As long as the finish is good and dry, you will be ok.
> 
> I went by Randy****1971 before this site had problems, so I just made another username and started over. Im the one that kept trying to get you to spray, LOL


Your just a late comer, several of us tried to get him to spray before there was even a williamwilliam. He must have good reasons, spraying would sure make the refinishing work a lot quicker and easier.


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## Quickstep (Apr 10, 2012)

I've rubbed out finishes using Micro-Mesh. It goes from 1500 grit to 12,000 grit. I follow that with Meguiar's Show Car Glaze. With poly, you do have to make sure your top coat is thick enough, or you'll get witness lines that will ruin your day. And, as others mentioned, the finish needs to be fully cured.


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## ColorStylist (Jul 19, 2014)

Steve Neul said:


> Your just a late comer, several of us tried to get him to spray before there was even a williamwilliam. He must have good reasons, spraying would sure make the refinishing work a lot quicker and easier.


OH, maybe I was williamwilliam too. My memory sucks! :smile3:


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## GAF (Nov 4, 2012)

ColorStylist said:


> What grit are sanding to before applying your last coat? I always block sand with 240 after the 2nd coat. I agree with what Epic said above, and it goes back to what I said earlier as well. Make sure you have a smooth surface before applying your final coat, and thin your final coat.
> 
> I would wait 48 hours before doing the brown paper bag rub. As long as the finish is good and dry, you will be ok.
> 
> I went by Randy****1971 before this site had problems, so I just made another username and started over. Im the one that kept trying to get you to spray, LOL




I sand my projects to 220 grit before starting the coloring and top coating processes. Between top coats I sand using either very fine sponge (which I assume is 320 grit) or actual 320 grit paper. I do thin the final coat or 2 coats.


As impatient as I am I will hold off 48 hours before using the paper bag.


Thank you for answering my personal question.


Oh yeah about that spraying thing I never did get there.


Gary


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## GAF (Nov 4, 2012)

Quickstep said:


> I've rubbed out finishes using Micro-Mesh. It goes from 1500 grit to 12,000 grit. I follow that with Meguiar's Show Car Glaze. With poly, you do have to make sure your top coat is thick enough, or you'll get witness lines that will ruin your day. And, as others mentioned, the finish needs to be fully cured.




Wow. This will also be something that I never get to. Waiting 30 days for curing would be too difficult for me.


Gary


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## Steve Neul (Sep 2, 2011)

GAF said:


> Wow. This will also be something that I never get to. Waiting 30 days for curing would be too difficult for me.
> 
> 
> Gary


All finishes take time to cure. Some cure faster than others and oil based finishes are not known to cure very fast. The molecules of the finish shrink and harden as they cure. Until then they are more porous with the ability for other chemicals to penetrate. By rubbing out a finish and waxing it prematurely it allows the wax to penetrate into the finish whereas when cured it would lay on the surface. This is why it is recommended a finish is fully cured before hand rubbing. If wax is allowed to penetrate into the finish it can cause a chemical reaction which could cause the finish to get cloudy or even fail prematurely. I don't do very much work with polyurethane because of this. I have let the customer have the furniture and at a later date picked up the furniture and polish the finish out. It's too much to ask someone to be without a table for a month and I don't want to damage the finish rushing it either.


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## GAF (Nov 4, 2012)

Steve Neul said:


> All finishes take time to cure. Some cure faster than others and oil based finishes are not known to cure very fast. The molecules of the finish shrink and harden as they cure. Until then they are more porous with the ability for other chemicals to penetrate. By rubbing out a finish and waxing it prematurely it allows the wax to penetrate into the finish whereas when cured it would lay on the surface. This is why it is recommended a finish is fully cured before hand rubbing. If wax is allowed to penetrate into the finish it can cause a chemical reaction which could cause the finish to get cloudy or even fail prematurely. I don't do very much work with polyurethane because of this. I have let the customer have the furniture and at a later date picked up the furniture and polish the finish out. It's too much to ask someone to be without a table for a month and I don't want to damage the finish rushing it either.


Steve that's a nice and detailed explanation. Thank you.

Gary


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