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Discussion Starter · #1 ·
OK, I know this is a bit of a stretch for the "Home Entertainment & Theater Builder" forum, but I have a feeling you guys can help. When I did the theater two years ago, I built an Oak bar in the lobby. Over the last two years, kids and parties have taken their toll on the finish. Yesterday, I sanded down the top using 240 grit paper and applied a coat of gloss poly urethane. When it dried this morning, the top bar was clear and near flawless, but the lower bar had small spots all over it where it looked like the poly didn't adhere.


Any thoughts on where I went wrong and how to correct?


Thanks,


Scott
 

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Did you use the same type of poly (oil vs. water based) as the base application? If you originally had an oil based poly then applied a water based poly on top, it might have issues adhering. I think oil-based on top of water-based is fine though.


I'm no expert but just a theory.
 

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Discussion Starter · #3 ·

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Did you use the same type of poly (oil vs. water based) as the base application?

Thansk Steve, yes, same type, but different sheen, I believe. I think the first couple coats was semi-gloss. Maybe that is the problem, but I don't see why since I sanded between coats.


Scott
 

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Then I'm not sure what happened. I hate that you might have to sand and re-poly again
 

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Are the "small spots" evenly disbursed along the base or are they in a splash type pattern? Is is possible someone dropped a drink or something at some point that spalshed on the base and dried?

Did you wipe the base down with a damp cloth after sanding and right before applying the finish? It's possible the base wasn't completely dry.

A couple of ideas.
 

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Discussion Starter · #6 ·

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I hate that you might have to sand and re-poly again

Thanks Steve. I think I'm in a new class called re-DIY'er. Seems I am having to do a few things over again
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Quote:
Did you wipe the base down with a damp cloth after sanding and right before applying the finish? It's possible the base wasn't completely dry.

A couple of ideas.

You know, that is possible. I did use a damp cloth to wipe down the sanded area. I will sand again tonight and wait a day then re-apply the poly. Thanks for the suggestion.


Scott
 

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I had a problem with my polyurethane application in my theater and called the manufacturer for advice. Moisture is definitely a factor. Too much and you can have blister and such, too little (as in humidity) and the poly doesn't cure properly. Another thing I was told was never use a tac cloth between coats of polyurethane. The wax in the tac cloth will mess with the poly's ability to bond to the surface. Don't know if this applies to your case. You might want to try sanding with a more aggressive sand paper also, something along the lines of 150 grit or higher. I hate having to redo this kind of stuff also.


Craigo
 

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Discussion Starter · #8 ·

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Too much and you can have blister and such,

That's exactly the term I was looking for. It's not like a raised blister, but like small pock marks where the poly didn't adhere. Also, never knew that about tac cloth. I thought that was exactly what you were supposed to use. I couldn't find any at HD when I was there yesterday, guess that's lucky I didn't.


Scott
 

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You might have what painters call "fish eye". This is usually caused when some type of contamination gets on the surface to be painted and causes the paint to "repel" from certain spots. The most common types of contaminants are wax and silicone (often used in furniture polish).


I suggest that you re-sand the area, and then clean the surface with a surface prep cleaner before your re-paint. 3M makes a cleaner called Prep-Sol, but I'm certain that your local paint store will sell something similar.


Good luck,

Scott
 

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Discussion Starter · #10 ·

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I suggest that you re-sand the area, and then clean the surface with a surface prep cleaner before your re-paint. 3M makes a cleaner called Prep-Sol, but I'm certain that your local paint store will sell something similar.

Thanks Scott. I'll sand and check for the cleaner tomorrow.


sds
 

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Quote:
Originally Posted by sdspga /forum/post/0


... Also, never knew that about tac cloth. I thought that was exactly what you were supposed to use. I couldn't find any at HD when I was there yesterday, guess that's lucky I didn't.


Scott

That's what I thought about tac cloth too. Kind of irritated me that the manufacturer of the poly I used didn't mention anything about it in their directions
. I was told to use a damp clean cloth to remove any sanding dust from the surface. Give it a few minutes to dry and apply the finish. That did by the way finally work. One other problem that plagued me was excess stain on my veneer. I don't believe that's an issue for you however.


Craigo
 
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