# Poly finish on oak plywood not building



## marino (Feb 26, 2016)

I got some oak plywood for a project that Im finishing that ive done some samples on. Im a beginner so i dont have a ton of experience but heres my problem. One of my samples I did 2 coats of stain (rust oleum wood finish) and 2 coats of poly (minwax wipe on) and the poly looks smooth like how it should. The other sample I just did one coat of the same stain and multiple coats of the same poly. On the sample that just has one coat of stain the poly just keeps absorbing into wood and not getting smooth like the other sample i did. I like the color of just one stain coat better but the poly keeps absorbing and looks un even and not smooth. Im trying to figure out how to get the poly smoother on 1 coat of stain like how the 2 coat stain sample I did. Whats going on here?? Did the 2 coats of stain fill in some of the pores so now the poly coats are smoother?? Any ideas?


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## Steve Neul (Sep 2, 2011)

What you have to understand is stain has linseed oil in it. When you put more stain on you put more linseed oil on too and it seals the wood to prevent the poly from soaking in so much. The problem is you want the poly to soak in so it bonds well to the wood. You shouldn't use more than one coat of a wiping stain. It's a bad habit to get into. If you manage to allow some of the stain to dry on the surface then the poly will adhere to the stain instead of the wood and peal off weeks or months later. 

The way to get the finish smooth with a wiping polyurethane is to apply enough coats on allowing each coat to thoroughly dry until it appears to have a coating on it. Then sand the finish with 220 or finer grit paper and keep applying coats sanding after each coat until you get the desired finish. When I say sand though it's not like sanding the wood the objective is just to smooth the finish. When you put a coat of any finish on wood the fibers of the wood tend to stand up making it feel fuzzy so you have to smooth it out as you go along. With a water based finish the wood gets even fuzzier. 

Using a wipe on finish takes more coats and more drying time between coats. The wipe on finish is much thinner than a brush on finish and is formulated to dry slower to give you more time to work it. Generally it takes three coats of a wipe on finish to equal one coat of brush on. Normally with one coat of brush on poly you sand after the first coat but since the wipe on is thinner you may have to apply three or four coats before you have enough to sand. If you sand too soon or too much you can sand through to the bare wood taking the stain off and that's really is very difficult to fix.


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## marino (Feb 26, 2016)

After I did my 1 coat of stain and let it dry for a day I wiped on a coat of the poly, it absorbed right in and dried in an hour so I wiped on another of poly. I let that dry for a day and then I barely even put 320 on it and there was some stain on the paper. I wiped off with mineral spirts and there was some stain on the rag. It lightened the color but not too badly. Ive since wiped on 2 coats of poly and now it seems like its starting to build but not real smooth. Should I sand inbetween every poly coat even while its still absorbing? or should I just sand when it starts to build smoother? Should I wipe with mineral spirits after I sand? Im concerned if I keep sanding after each coat before its built up then I lose some stain color. Also Id like to mention the sample stain is Rust Oleum Ultimate Wood Stain Kona, its a dark brown.


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## Steve Neul (Sep 2, 2011)

You're sanding too soon is the problem. There should be a plastic film there to sand. It should sand to a white powder. Also you should not be wiping with paint thinner. If the finish isn't completely dry you can be removing finish. Use only a clean dry cloth or compressed air. An hour isn't enough drying time for polyurethane, especially wipe on. It may feel dry but is still wet in the wood. Go by the directions on the product and add 50% or more when the weather is cool and or damp.


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## marino (Feb 26, 2016)

I am sanding too soon? The can says sand after first coat. What if I sand very lightly after first coat and there is stain color on the paper? Would it be better to do 2 coats within a day and then sand after that? I guess ill just keep experimenting on these samples to figure it out.


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## Steve Neul (Sep 2, 2011)

marino said:


> I am sanding too soon? The can says sand after first coat. What if I sand very lightly after first coat and there is stain color on the paper? Would it be better to do 2 coats within a day and then sand after that? I guess ill just keep experimenting on these samples to figure it out.


From here it's difficult to tell you when to sand. Every different finish works a little different however I think with any wipe on finish sanding after the first coat is too soon. You just have to wait until the wood appears to have a plastic coating on it to sand. It's about the worst thing you can do to sand through the finish to the bare wood and sanding, even lightly is risking doing just that. As a rule you should never ever get stain on the paper sanding between coats. You use that as a warning sign to quit what you are doing. 

If the finish will completely dry after applying two coats in a day then you might be good to do a light sanding. Usually when you sand before a finish is dry enough little balls of finish will gum up on the paper. This is a sign it's not dry enough to sand. The finish when sanded should make white dry dust. You have to be careful rushing the drying time. If you apply coat after coat of finish before it's completely dry the outer surface will harden first and what is underneath will take a very long time to harden. This can results in dents in the finish from something heavy sitting on it pressing into the finish. In some cases when the underlayers shrink and harden it causes the outer layer to crack like tempered glass. Each layer needs to harden before proceeding to the next layer. 

What would make your finishing experience a great deal easier would be to get some spray equipment and use lacquer for a finish. In warm weather you could complete a finish from beginning to end in three hours or less.


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## HowardAcheson (Nov 25, 2011)

I believe that your problem is that you finished the two pieces differently. When you want to have surfaces look alike, you must finish each exactly the same using the same products and the same number of coats. 

What I would do now is to use a chemical paint remover and take off all the finish from both pieces. Now sand both pieces using the same progression of grits. Finally, apply the same number of coats of the same products to both pieces. This is the easiest way to assure getting the same coloring on both pieces.


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## epicfail48 (Mar 27, 2014)

marino said:


> I am sanding too soon? The can says sand after first coat. What if I sand very lightly after first coat and there is stain color on the paper? Would it be better to do 2 coats within a day and then sand after that? I guess ill just keep experimenting on these samples to figure it out.


For a wipe-on poly, yes. I never sand the first coat of any finish, and wipe=on poly, this as it is, i dont touch until at least the third coat


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