# Trouble with polyurethane



## hokeyplyr48 (Nov 12, 2013)

My dad taught me to finish with polyurethane by putting on a couple coats with a foam brush and at the end hitting it with some #0000 steel wool.

I did a work bench that was a really light color in a satin finish and it turned out great and smooth.

However, I'm doing another project and it's a much darker finish. I stained it with an oil based red-mahogany color. The stain turned out great and I'm moving into the polyurethane stage.

I started out with the old method and brushed on a couple coats of polyurethane and then hit it with the steel wool. But it just destroyed the semi-gloss finish I'm trying to achieve and it looked really cloudy/dull. So I began researching and came across this website. I google searched and read just about every thread that mentioned poly or polyurethane for the last 5 years on this forum.

A few members talked about wet sanding up to 1000-2000 and then using abralon discs. One member posted these two videos as well:
https://www.youtube.com/watch?v=zN-9vCSJWDQ
https://www.youtube.com/watch?v=aV9y44JXXGU
I watched these videos and am in the process of attempting to replicate it.

At this point I have done:

3 coats with a foam brush
sanded with 0000 steel wool
wipe on coat of polyurethane thinned with naphtha
wet sanded with 400 grit sand paper
Repeat the last two steps about 3 times

It looks really awesome after I finish with a wipe on coat of polyurethane except there are some bubble holes that are left that I've been attempting to fill in with the last couple wipe on coats. After 1 or 2 more wipe on coats it should be completely flat (hopefully). It looks awesome, but at this point it doesn't feel smooth like glass:









If I wet sand, it feels really smooth like glass but it has a milky look to it. It looks splotchy like this:









After I fill in all the little holes and dry sand it to an even surface with 400grit, my process I think is:


wet sand with 800 grit
wet sand with 1000 grit
wet sand with 1000 grit abralon pad

*Does this sound right? Is there anything I should do differently?*

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Also, I have been working on this same board for about two weeks now and it is taking forever. I'm looking to streamline this process so it quickens since I have a whole lot more to finish.

*For the new pieces should I?:*

thick coat with foam brush (should I thin it at all?)
sand with 400 grit
brush second coat on
sand with 400 grit
wipe on a coat or two
wet sand with 400 grit
wet sand with 800 grit
wet sand with 1000 grit
wet sand with 1000 grit abralon

Any help would be most appreciated!!


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## TaleSspin (Jan 7, 2013)

Firstly, if you are using 400 grit as a "finish sand" that is not going to give you a glassy look. You are going to have to transition from a sanding, to buffing, to polishing. Results are also going to differ if you are using a finish with flattening agents in it (i.e. "satin"). If you want a pure, glass look, the best bet is to use something labeled "high-gloss" or make your own. High-gloss usually denotes it as a pure varnish (plus solvent of course) that does not have added flattening agents. Honestly, you can achieve what you are looking for with just a few coats of gloss or high-gloss and skip the final sand -- I don't want to say your dad is wrong, and lots of people do things different, but I have never had a need to sand a final coat.

As for the picture and milky finish, it looks to me like you might have had a bonding issue between coats. It's hard to tell by a picture. I suspect you may have neglected to sand between coats. You mention "3 coats with a foam brush" but no sanding in between. It's important for not only a smooth finish (to remove particles that settle on the surface between coats) but also to abrade the surface to facilitate bonding of the layers. Polyurethane varnish does not chemically bond between coats, it mechanically bonds; so unless it has something to grab - like a surface scuffed with 400grit - it may not bond effectively. (Someone please correct me if that is wrong)

You did mention sanding between in your final section for the next pieces, in contrast to not mentioning that in your previous steps. Again, if you did not sand in between coats, you really ought to.

I honestly think you are over-thinking the finishing and putting in more work than needed. As I said, 3 coats of gloss or high-gloss, sand lightly at 400-600grit (doesn't matter really) between, your final coat should be applied nice and thin and leave it alone. Should shine nicely. 

If you want to go through a lot of work buff for a mind-lowing shine, I've found no better source than this: 




Steve is very thorough in explanation here and this is way beyond what even most professionals are going to go to. So if that's what you want, there's that!


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## punkin611 (Sep 17, 2013)

hokeyplyr48 said:


> My dad taught me to finish with polyurethane by putting on a couple coats with a foam brush and at the end hitting it with some #0000 steel wool.
> 
> I did a work bench that was a really light color in a satin finish and it turned out great and smooth.
> 
> ...


 You seem to have contamination under you stain, maybe wood glue? You have done way more work than I would have. There is many ways to skin a cat but don't work so hard.


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## Steve Neul (Sep 2, 2011)

It just looks to me like you took the sheen off with the 400 grit paper. If the intention is to rub the finish out 400 grit is just too coarse. If you have enough thickness of finish you could re-sand it with 1200 to 1800 grit paper and buff the cloudiness out with rubbing compound. It would probably be safer though to put another coat on then wet sand it with the finer paper. You would also be better off using 220 grit paper after the first coat rather than using steel wool. If there is any debris in the finish the steel wool won't sand it off.


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## hokeyplyr48 (Nov 12, 2013)

Thanks everyone for the helpful posts so far! I figured out what exactly was going on and learned some stuff from reading your posts. I didn't know polyurethane used mechanical bonding instead of chemical.

But the milkiness was just the sheen coming off from the semi-gloss finish due to the sandpaper. I didn't entirely understand the whole process until watching the chessboard video that was posted which was extremely helpful. So I kinda had the steps right but because I didn't understand the theory, I didn't know what was wrong and what was happening.

The weird design was actually due to the polyurethane not being completely flush so some parts were still glossy because the sandpaper hadn't touched it because it was lower. I also learned and saw that the grain really soaks up the polyurethane and that it's going to take some thick coats before everything will really level out. I sanded too aggressively this time in order to try and get all the glossy parts to turn into the matte finish showing that everything was level and hit into the stain. Good thing this is a practice piece.

So at this point I'm hitting it with a thick coat, then sanding to get flush and matte all the way across to go through the finer grits of sandpaper and then into the abralon.

I'll keep you guys posted and hopefully I won't have any more issues or questions. Thanks again for all the insight and advice!


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## TylerJones (Dec 4, 2011)

If you are trying to build up a finish thick enough to truly flatten the surface you are going to run into problems with oak, especially rotary cut veneer like you are using. You need to use a grain filler if you want to fill the pores. I tend to think you are taking the long way around with your process but I don't know what the pieces are for so I'm not going to go into a full finishing schedule. If you would like one post a little info about what you are trying to achieve and I'll post one that will fit. I do high end finishes for a living in addition to building furniture.


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## hokeyplyr48 (Nov 12, 2013)

TylerJones said:


> If you are trying to build up a finish thick enough to truly flatten the surface you are going to run into problems with oak, especially rotary cut veneer like you are using. You need to use a grain filler if you want to fill the pores. I tend to think you are taking the long way around with your process but I don't know what the pieces are for so I'm not going to go into a full finishing schedule. If you would like one post a little info about what you are trying to achieve and I'll post one that will fit. I do high end finishes for a living in addition to building furniture.


Wow you hit the nail on the head, it is an oak veneer. I am trying to level the surface so I can do the nice sanded finish and use the abralon pads to finish it off. I can't leave the top coat on because I always have dust that gets into the finish (All I have available is my garage) and the wet sanded finish feels like glass whereas the unfinished polyurethane top coat just never has that smooth finish.

I keep putting on layers and sanding it to level the surface and it is taking forever, at this point I keep feeling like I'm not making progress. As you can see in the picture below, I still have some low spots which reflect the light because they still have the semi-gloss finish. I also went through the polyurethane in a few spots which took the stain away which ruined the finish  It's on a non-visible face, but it still sucks and would like to avoid it for the rest of the pieces since the rest of them I won't get so lucky.









Now I have two questions, for the two pieces that I already have started to do the polyurethane on, what can I do to get the surface level so I can do the finishing? Or is that a lost cause and just put the polyurethane on it and leave it as is because it's impossible to finish now?

With the other pieces that have been stained, but no polyurethane yet, can I apply the wood grain filler now? Or since it's been stained is it too late? How would you recommend finishing these pieces in order to get the surface level from the start so I can go through the sanding process to get the glass smooth finish?

Any help would be most appreciated!!


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## cabinetman (Jul 5, 2007)

At the stage you are at now, I would use a solvent based grain filler. Follow directions on the label. Once you have that stage done, you can start applying the finish. I would recommend wiping on, and in thin applications...not heavy coats. Let each cure. You can sand in between coats with 320x. When you have sufficient build, you can start the wet sanding with wet-or-dry silicone carbide paper, with a block and water. Use graduating grits up to 1500x. By that time, very little rubbing with rubbing compound will be needed. 

You could use an automotive type compound, and for the last bit of polishing a polishing compound.

















.


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## TaleSspin (Jan 7, 2013)

hokeyplyr48 said:


> I can't leave the top coat on because I always have dust that gets into the finish (All I have available is my garage) and the wet sanded finish feels like glass whereas the unfinished polyurethane top coat just never has that smooth finish.


Judging by the size of your project you could just get a large box and invert that over your project after you apply the final coat. That should eliminate most all the issues with particles settling on it. 

If this is something you are wanting to get in to more you might consider investing in a homemade "paint/finish booth." PVC pipe, visqeen, and a box fan + furnace filter. 

If you're interested in pursuing something like that there is oodles of info and examples online, lots of guides on youtube too. It's something I've been looking in to recently.


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## hokeyplyr48 (Nov 12, 2013)

cabinetman said:


> At the stage you are at now, I would use a solvent based grain filler. Follow directions on the label. Once you have that stage done, you can start applying the finish. I would recommend wiping on, and in thin applications...not heavy coats. Let each cure. You can sand in between coats with 320x. When you have sufficient build, you can start the wet sanding with wet-or-dry silicone carbide paper, with a block and water. Use graduating grits up to 1500x. By that time, very little rubbing with rubbing compound will be needed.
> 
> You could use an automotive type compound, and for the last bit of polishing a polishing compound.


Thank you for the suggestion on the wood grain filler, I didn't even know it existed before your post. I just figured the polyurethane would cover it over and seal it. I did a whole bunch of research on wood grain filler and came across Aqua coat clear grain filler. Charles Neil strongly recommended it. On the aquacoat website, it says you can use it after staining. Since the rest of the project is already stained, I will apply that to the grain to fill the pores so I can get my level surface.

http://intheworkshop.wordpress.com/2011/09/29/aqua-coat-grain-filler-its-a-keeper/
http://aquacoat.com/?page_id=43

*For my current situation with these two boards that aren't exactly coming out level with the finish should I:*

Take polyurethane and using a brush put it on all the low points in attempts to bring them up to the same level as the surrounding areas? I've been adding coats to the entire board and sanding it down and it is not really making much progress and is taking forever
Or use the aquacoat and apply it to the low/still glossy areas in order to bring it up to the level surface



TaleSspin said:


> Judging by the size of your project you could just get a large box and invert that over your project after you apply the final coat. That should eliminate most all the issues with particles settling on it.
> 
> If this is something you are wanting to get in to more you might consider investing in a homemade "paint/finish booth." PVC pipe, visqeen, and a box fan + furnace filter.
> 
> If you're interested in pursuing something like that there is oodles of info and examples online, lots of guides on youtube too. It's something I've been looking in to recently.


Thanks for the tip, I've done some googling and may end up setting something like that up. I had started researching air filters to see if I could just let it run in the garage to filter the dust out of the air but this seems like the way to go.


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## hokeyplyr48 (Nov 12, 2013)

Just wanted to say thanks for the help and advice in this thread. I ended up throwing on a few more coats and sanded till level. Then wet sanded up to 2000 grit then used abralon pads in 1000 and 2000 grit. Result is slick as glass and looks great:


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## TaleSspin (Jan 7, 2013)

Looks slick! Good job mate!


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