# rubbing out water based poly?



## j10c3y25 (Jan 8, 2014)

So I'm down to what should be my last coat of poly, but I can't seem to get it right. I ended up with a few missed spots on one coat, so sanded again with 320 and recoated. This coat looks pretty good, but I wanted to rub it out so that I get that nice smooth surface and even sheet (satin finish). I tried wet sanding with 400, and then 1200, and it looked like crap. Then I realized I skipped 600, so I went back down to that thinking it could be the problem. Still not very good looking. So the only thing I can think of is that I'm not starting with a low enough grit to achieve a polished surface. I felt around and there are a few spots where I messed up early on and sanded to the wood, the poly seems to have built up here and made small ridges (peaks). That and this is my first time doing any finishing so my coat thickness and application has not been uniform by any means, though I've pretty much got the hang of it now thanks to some advice, videos, and 5 or 6 tries.

So my questions are

1. CAN you rub out a water based brush on poly?

2. Do I need to start with 320 and completely level the surface before I move up to 400, 600, 1200?

3. For a satin finish do I stop at 1200 or do I need to further polish with a compound or some such?

4. I planned to apply a paste wax to improve the final look after polishing, how should I prepare the surface for it?

Because I know I will be asked, here is what I've done, as well as I can remember it.

From raw wood, sanded completely with 60, 100, 150, 220. Wiped on trans tint mixed with denatured alcohol, didn't wipe off excess, allowed to dry for ~3 hours (Arizona, its hot and dry here so drying times are pretty fast). Applied first coat of poly with brush, it mixed together with some of the dye, not causing any finish problems but sure made cleaning difficult. Dried for 12 hours, sanded with 220, which was too aggressive and went through the finish in a few spots. 2nd coat with brush, dried for 3 hours, sanded with 400 which wasn't aggressive enough, bought some 320 later. Applied third coat, dried 3 hours, sanded with 320. Applied 4th coat and decided it would be my finish coat for everything except the top which would get one last coat for extra protection. Sanded with 320, applied 5th coat to top, just barely ran out of product and the coat was too thin, I missed some spots. Dried 3 hours, knocked it back down with 320, applied 6th coat to top, dried for 12 hours. And so here we are. I still ended up with a few streaks/witness marks, and I think even my last coat wasn't quite thick enough. I've already sanded it with 320 pretty thoroughly to try and level it as much as possible so I don't end up with more witness marks. I was thinking I'd just put another coat on and then try to rub it out.

Am I on the right track here?


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## WillemJM (Aug 18, 2011)

Those sure are a lot of coats.

I only sand the first, apply another two, touch up any bad areas lightly with 400 paper and then go to a 3M auto buffing compound by hand.

For aggressive buffing, WB takes a long time to cure properly, some suggest a month. With all the coats you applied you may want to wait a bit before final sanding and buffing.


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## Steve Neul (Sep 2, 2011)

j10c3y25 said:


> So I'm down to what should be my last coat of poly, but I can't seem to get it right. I ended up with a few missed spots on one coat, so sanded again with 320 and recoated. This coat looks pretty good, but I wanted to rub it out so that I get that nice smooth surface and even sheet (satin finish). I tried wet sanding with 400, and then 1200, and it looked like crap. Then I realized I skipped 600, so I went back down to that thinking it could be the problem. Still not very good looking. So the only thing I can think of is that I'm not starting with a low enough grit to achieve a polished surface. I felt around and there are a few spots where I messed up early on and sanded to the wood, the poly seems to have built up here and made small ridges (peaks). That and this is my first time doing any finishing so my coat thickness and application has not been uniform by any means, though I've pretty much got the hang of it now thanks to some advice, videos, and 5 or 6 tries.
> 
> So my questions are
> 
> ...


Yes you can rub out a water base polyurethane but not to satin. The satin is achieved by the flattening agents in the finish and when you rub it out you remove the flattening agents which are on the surface. The finish really needs to be applied and left alone. Spraying the finish is the best method for a satin finish. If that isn't an option perhaps the last few coats you might use a wipe on water based satin poly. It will apply better than brushing. 

When you rub a finish you need to get the finish in great shape before the last coat because when you sand the final coat you need to start with 1200 grit paper and perhaps finish with 1500 to 2000 grit paper. The coarser paper even 600 will make scratches in the finish you can never buff out. The final finish is achieved by rubbing the finish out with rubbing compound and the sheen brought back with wax. Even a satin poly will come out shinny with this procedure. 

A finish may feel dry and you can sand it and work it however it's not dry enough for any kind of wax. If you apply wax before the finish is cured it penetrates too far into the finish and can damage the finish. Most any finish takes a month before it is cured enough for wax.


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## Quickstep (Apr 10, 2012)

I've had good luck using MicroMesh to achieve a variety of sheens on a variety of finishes. As you already mentioned, it's important to not skip grits. MicroMesh starts at 1500 and goes to 12000. So, the first step is to work through grits until you can start with the MicroMesh 1500. If your surface is reasonably good, I think you can start around 500 or 600. The finish need sot be fully cured. If sanding leave corns or boogers on your sandpaper, it's too soon. A good felt or foam sanding block is a must. I use naphtha as a lubricant, but be careful, it's very flammable. (if you choose a foam sanding block, make sure the naphtha doesn't dissolve it). You can sort of "feel" when each grit has done its job. Take your time and wipe between each grit to remove the slurry of sanded finish. Each time you wipe off, you get to see if there are places where sanding lines from the previous grit are still evident and if you've achieved the sheen you like. In most cases, you can just sand to around 4000 or 6000 and end up with a pretty nice satin. Alternatively, you can sand all the way to 12000 to really get things level, then work your way back down the grits until you get the level of satin you want. 

One last note of caution......

Find out if your waterborne poly crosslinks between coats. If not, and you sand through to the previous coat when sanding out, you may see "witness lines" which show the spots where you sanded through the finish coat to the coat below. 

Here's a link to MicroMesh. They also make little foam pads which are great for polishing the finish on pens on the lathe, but for larger surfaces, you need the kit in the link.

MICRO MESH SANDING SHEETS INTRODUCTORY WOOD KIT - Amazon.com


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## j10c3y25 (Jan 8, 2014)

Ok, so I put on my most uniformly applied coat to date on the top after having leveled it down with 320 through all the junk I messed up on. If I'm understanding correctly, as long as there are no major flaws in my finish then it should be possible to rub out, but I'll need to wait for the poly to fully cure. I had not realized the drying time was so long, nor how much it could effect polishing, but it does make sense. I've found several articles and seen lots of advice and the most common one is sand with 600 and then wax with 0000 steel wool. I think It would make a lot more sense to go with sandpaper up to 1200 (I'm thinking 600, 800, 1000, 1200) before touching it with wax. Either way, it seems like everyone has their own way of doing it and they ALL work.

Now the question is what constitutes a flaw that I cannot buff out? When I look at the surface it is, for the most part, clear and shiny. There are a few spots that look dull as if I had missed them, though there is plainly poly on them, and I really don't think it should be necessary to put ANOTHER coat on. If it is in fact a witness mark, then can I just touch it up with a dab of poly, or can I leave it alone and take care of it in the buffing process?


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## cabinetman (Jul 5, 2007)

Depending on the brand some work and look better than others. They finish much better if sprayed than brushed or wiped on. I don't sand the first or second application. I use 320x between applications from that point forward. Most brands will lay out better if reduced a bit with water...about 5%. Like wise if you want some 'burn in' many brands can take about 5% lacquer thinner. Test your media to see what works best.

If I'm to 'rub' out the finish, there has to be sufficient build to sand out the final application. It can be rubbed out to an almost flat sheen, or a high gloss clear. Wet sanding to high grits...1500x will take very little rubbing with a rubbing compound. I use automotive compounds. The reds are on the coarse side, and the whites are a smooth polish. 

I don't use any wax, and wouldn't suggest it, as that is only a temporary enhancement. If wax is used that would preclude any further finishing if it became necessary without extensive steps to remove it.








 








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