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Getting dull streaks w/Satin Poly

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Forum topic by optimusprimer92 posted 03-16-2017 02:08 AM 401 views 0 times favorited 7 replies Add to Favorites Watch
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optimusprimer92

21 posts in 396 days


03-16-2017 02:08 AM

Hey all. I am trying to complete a counter top for our washroom and am having trouble with the finish coat. I am using maple ply for the top that I stained w/ black India Ink. I sealed that with some spray shellac. Now I am doing the main finish which is Minwax Clear Satin Poly. I have applied about 5 coats. The first was an undiluted coat with a brush. Second and third were diluted 50/50 w/ mineral spirits and wiped on. The streaks were HORRIBLE after I wiped on the thinned poly. I sanded between coats 1/2 and 3/4 w/ 400 grit sand paper. I just applied another thin coat of undiluted by wiping it on. Now that it is drying, I can see I once again have horrible dull streaks in the finish. How do I avoid/remedy this? I stirred the can about 200 times with this last coat to see if that would help but alas, it did not. Any ideas?


7 replies so far

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Monte Pittman

27049 posts in 2172 days


#1 posted 03-16-2017 02:32 AM

My first thought would be that it’s not stirred properly. Should be properly stirred every time the can is opened.

-- Mother Nature created it, I just assemble it.

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optimusprimer92

21 posts in 396 days


#2 posted 03-16-2017 02:34 AM

I stirred the can for about 2 minutes prior to using for the last coat.

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squazo

51 posts in 1479 days


#3 posted 03-16-2017 02:50 AM

are you sure these streaks are sanding marks. I had this happen once to me on a dark surface, because sanding poly turns it kind of white, like scratching plastic (which it is). I think I worked up to 1000 grit and still had sanding marks which were visible, and white and looked a lot like you picture. I ended up having to sand all the poly off and using lacquer because you don’t have to sand in between coats of lacquer. I was trying to poly over 8 coats of flat black paint which I polished up to 3000 grit, after I got rid of the poly and used brush able lacquer and polished and buffed the lacquer I can use the counter top as a mirror

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optimusprimer92

21 posts in 396 days


#4 posted 03-16-2017 02:58 AM

The marks are definitely from the poly application, not sanding marks. The streaks are like smudgy smear marks from where the poly was wiped on.

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squazo

51 posts in 1479 days


#5 posted 03-16-2017 03:24 AM

the only other thing i can say is that once the smear marks are there, they are there you are going to have to sand them out. that undiluted coat you wiped on last isn’t going to get rid of previous smear marks. maybee try sanding it until it looks good and then try another coat. also check all the materials you are using and make sure they are in date if it has a shelf life and that nothing is the wrong chemical in a can, kind of like whats the first thing you do when your car dies, check for fuel.

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JBrow

1272 posts in 754 days


#6 posted 03-16-2017 11:24 AM

optimusprimer92,

I cannot say what caused the problem but offer some ideas. First is the mineral spirit spirits solvent itself. I have found that the home centers around me only carry reduced odor mineral spirits. The product tends to be cloudy suggesting that whatever is added to the mineral spirits is insoluble and if deposited on a surface mixed with polyurethane, could be incorporated into the cured finish leaving it dull. But this by itself does not explain why there is streaking; I would think the entire surface would be dull.

My second thought is that a 50/50 dilution of polyurethane would reduce its viscosity allowing the particulates in the satin polyurethane to settle faster than they would settle in undiluted polyurethane. As the rag is dipped in the application bucket, sometimes few of the light diffusing particles of the polyurethane could be transferred to the rag while a second dip of the rag could pick up more of these light diffusing particles. Much more frequent stirring of the diluted polyurethane in the application bucket could be required to keep the particles suspended.

My last thought is that the rag could retain some of the polyurethane’s light diffusing particles. But as the rag dries out as the poly is wiped on perhaps more of these particles flow onto the surface.

Whatever the cause, I think that squazo is correct. To remove the streaks, the finish will have to be sanded at least to the first coat of applied poly.

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optimusprimer92

21 posts in 396 days


#7 posted 03-16-2017 04:43 PM

Thanks for the replies. I sanded everything down today…including some of the veneer of the plywood underneath…SMH. I will reapply some more ink to try to cover up the blemishes and redo the finish with some Gloss-poly. I have read that it is easier to get streak free with it.

On another note, I am sorely disappointed with the $120 A-1 Maple ply I used for the counter top. It has the thinnest, least consistent veneer I have ever encountered and along with all the bumps and raises in the surface, I would have rather used a $40 sheet of Chinese pine from Home Cheapo.

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