# Bubbles in Minwax oil polyureathane



## jjrbus (Dec 6, 2009)

Let me start with I am not a professional but have been using poly here and there for ?? not even sure 40+ years.

One thing I have noticed is I use to put lots of thinner on my brush and wrap it in clear plastic food wrap, it would stay good for a few days, now a day at the most. Something changed?

I am doing a third coat of poly on 7 oak cabinet doors, I am doing the 3rd coat because there was many small missed areas on the second. OK my eyesight is not what it used to be, I was in a hurry, who knows? Yes I used a handheld light at an angle.

I open the can of Minwax fast drying clear satin poly that I have been using mix in a bit of mineral spirits, and coat the first door, no issues. I coat the second door and look at the first, bubbles, maybe 50/60 huge bubbles, What the? OK I lightly brush the door again and the bubbles are gone. 

I coat the third door, look at the first and second door, 20/30 bubbles on the first door. Second door is fine. I lightly rebrush the first door and the bubbles are gone. 

I coat the fourth door and the first door has maybe 10 large bubbles on it. Rest of the doors are fine. I am thinking it is too late to brush this one again, I am going to let it dry and sand it.

Any way no problems with the rest of the doors only the first. I am baffled, I do not remember anything like this before, of course I do not remember alot anyway.

When I read about people getting bubbles in finish, I am thinking little tiny pin head bubbles, not Godzilla ones.
JIm


----------



## Steve Neul (Sep 2, 2011)

Bubbles in a finish are normally caused by the finish being too thick or applying it too thick. The depth of the craters suggests to me the problem is the finish was applied too thick. With any polyurethane it's best to apply as thin a coat as you can with as few strokes as possible. Using a very soft brush is also helpful on the overall outcome.

The good news is it looks like there is sufficient finish there you can wet sand the bubbles out and put another coat on.


----------



## jjrbus (Dec 6, 2009)

Thanks for the response. I took a piece of scrap and before I thinned the poly, brushed it on as thick as I could, not one bubble!!Did the same thing after I thinned it, again not one bubble?

I am not sure if it is me or the Minwax, but I am not happy with the results this time. I do not want to change brands in the middle of a project, but will experiment with a different brand next project. Probably Sherwin Williams poly.

Thanks JIm


----------



## cabinetman (Jul 5, 2007)

It looks like the poly was draining into voids in the dark grain, leaving air pockets. Once it has cured, wet sand and wipe on thin applications.


















.


----------



## Steve Neul (Sep 2, 2011)

jjrbus said:


> Thanks for the response. I took a piece of scrap and before I thinned the poly, brushed it on as thick as I could, not one bubble!!Did the same thing after I thinned it, again not one bubble?
> 
> I am not sure if it is me or the Minwax, but I am not happy with the results this time. I do not want to change brands in the middle of a project, but will experiment with a different brand next project. Probably Sherwin Williams poly.
> 
> Thanks JIm


Did you use standard mineral sprits or the low odor stuff? I haven't found a finish yet that will work with low odor mineral sprits. It may have been just a fluke. The rest of the poly around the spots look fine. The fast dry poly will be more prone to do that the slow dry because it sets up faster. 

Personally I don't like thinning poly. I thin it for the first coat and then use it full body for the rest of it, even spraying it.


----------



## jjrbus (Dec 6, 2009)

Yes, Klean strip orderless mineral spirits and Minwax fast dry poly from the big box store.

Is the old fashioned stuff available any more? Thanks for the response. JIm


----------



## cabinetman (Jul 5, 2007)

jjrbus said:


> Yes, Klean strip orderless mineral spirits and Minwax fast dry poly from the big box store.
> 
> Is the old fashioned stuff available any more? Thanks for the response. JIm


I haven't had a problem with the low odor, and the box stores here still sell the regular mineral spirits.


















.


----------



## HowardAcheson (Nov 25, 2011)

Is this new, previously unfinished wood? If not, what was the existing finish on the item? What did you do to remove the existing finish?

To answer another question you asked: Yes, all oil based finishes are constantly being re-formulated these days. The finish manufacturers are attempting to remove as much VOC's as possible and formulations are changing all the time.

It's important to read the label instructions and try out the finish on scrap wood before committing to your actual item. Do not assume that your recently purchased finish will behave the same way older finishes did


----------



## jjrbus (Dec 6, 2009)

Thanks for the response. This is new wood and this is the third coat of poly from the same can I have been using.
Thanks JIm


----------



## Steve Neul (Sep 2, 2011)

jjrbus said:


> Yes, Klean strip orderless mineral spirits and Minwax fast dry poly from the big box store.
> 
> Is the old fashioned stuff available any more? Thanks for the response. JIm


I haven't found any finish the low odor mineral spirits is good for. The Kleen Strip is one of the brands I have tried and disposed of. It doesn't seem to mix with the finish like it was incompatible. There are some states like California which have banned the solvent. I'm in Texas where standard mineral spirits is available anywhere including walmart.


----------



## jjrbus (Dec 6, 2009)

Did a bit of surfing, seems low odor MS is refined more than regular MS.

On the surface I would think furthur refining would not be an issue? But that is an opinion, not knowledge. 

So I will poke around a bit and see if I can find some old fashioned stinky MS!! And do a scientifically controlled esperiment.

Even without the bubble's, which must have been a quirk, I am not happy with the finish I am getting.

Maybe it is me?? The golden years are tarnished. JIm


----------



## sgreer13 (May 17, 2014)

Sorry to add my own question to an open thread but Im experiencing the same problem. I admittedly added a thick coat of poly with the intention of rubbing it out on a coffee table I built. I managed to get 5 or six little bubbles (smaller that the above) photo. My question is would you recommend sanding it smooth and adding another layer or can I proceed to rubbing it out and just rub out the bubbles? Also would anyone care to comment on how to best rub out poly? Im looking for a satin sheen nothing glossy. My plan was to start by wet sanding with 400 grit paper and finishing it with 0000 steel wool lubricated with soapy water and finish it off with some furniture paste wax? This is my first project and I was wondering if I'm on the right track?

~mick


----------



## Steve Neul (Sep 2, 2011)

sgreer13 said:


> Sorry to add my own question to an open thread but Im experiencing the same problem. I admittedly added a thick coat of poly with the intention of rubbing it out on a coffee table I built. I managed to get 5 or six little bubbles (smaller that the above) photo. My question is would you recommend sanding it smooth and adding another layer or can I proceed to rubbing it out and just rub out the bubbles? Also would anyone care to comment on how to best rub out poly? Im looking for a satin sheen nothing glossy. My plan was to start by wet sanding with 400 grit paper and finishing it with 0000 steel wool lubricated with soapy water and finish it off with some furniture paste wax? This is my first project and I was wondering if I'm on the right track?
> 
> ~mick


It is unlikely you can rub a bubble out. Polyurethane goes on in layers and probably by the time you sand the bubble out you will be down to the layer below it. The sand through even though not down to the wood will show up no matter how you polish it. 

If you are wanting a satin finish I would use a satin poly for the final coat and not rub it out. The finish not rubbed out will have a more consistent sheen. The flattening agents in the finish float to the surface as it dries and if you rub the finish you end up making it shinny in spots as you tend to rub more in center of open areas. When you sand between coats use only water. Soap has a certain amount of oil and can cause adhesion problems. When you sand to polish a finish start with 2000 grit or finer paper. 400 grit is too coarse. It makes scratches in the finish which is very difficult to rub out.


----------



## sgreer13 (May 17, 2014)

Steve Neul said:


> It is unlikely you can rub a bubble out. Polyurethane goes on in layers and probably by the time you sand the bubble out you will be down to the layer below it. The sand through even though not down to the wood will show up no matter how you polish it.
> 
> If you are wanting a satin finish I would use a satin poly for the final coat and not rub it out. The finish not rubbed out will have a more consistent sheen. The flattening agents in the finish float to the surface as it dries and if you rub the finish you end up making it shinny in spots as you tend to rub more in center of open areas. When you sand between coats use only water. Soap has a certain amount of oil and can cause adhesion problems. When you sand to polish a finish start with 2000 grit or finer paper. 400 grit is too coarse. It makes scratches in the finish which is very difficult to rub out.



Thanks for the reply, I think I will just try to put on another coat carefully. I agree that the satin poly goes on very nicely...if it weren't for the bubbles I think I would have foregone the final rub out any way. Do you have any recommendation for how to lay down the poly? My first coat was with a china tip brush--> brush stroke but no bubbles, second coat with foam brush--> no noticeable flaws (to me at least), my final coat was very thick and I layed it down with a foam brush and it was a little dark so the finish was starting to cure before I caught the bubbles. Thanks again


----------



## Steve Neul (Sep 2, 2011)

sgreer13 said:


> Thanks for the reply, I think I will just try to put on another coat carefully. I agree that the satin poly goes on very nicely...if it weren't for the bubbles I think I would have foregone the final rub out any way. Do you have any recommendation for how to lay down the poly? My first coat was with a china tip brush--> brush stroke but no bubbles, second coat with foam brush--> no noticeable flaws (to me at least), my final coat was very thick and I layed it down with a foam brush and it was a little dark so the finish was starting to cure before I caught the bubbles. Thanks again


I've never been able to use a foam brush with clear finishes. It seems to always cause bubbles for me. If you are going to use a brush with the poly it's important to put it on as thin as you can with as few strokes as possible. The more you brush it the faster it sets up and more prone to get air in it. If you do see a few bubbles in the finish, there is no reason you can't pop the bubbles with a pin while they are fresh. The finish should flow back together. For me the best way to put poly on is to spray it. Doing it by hand it's better to use a wipe on poly. That way it goes on so thin brush marks are not so much an issue. It's also a good idea working with any kind of satin finish that you use a gloss finish first and when you think you are to the last coat then use satin. The flattening agents that make the finish satin will also make the finish more cloudy with multiple coats where the gloss is clear. The stuff that makes the finish satin looks more like baby powder is why it clouds the finish if you get it on too thick.


----------



## cabinetman (Jul 5, 2007)

At this point, I would do a scuff sanding and thin the poly to a wiping viscosity. I would use a lint free tee shirt type cloth folded into a neat pad. Those bubbles I'm guessing are pockets in the grain that the finish gets drained into. If you continue to load those areas, they will continue to bubble. If you had used a paste wood filler, or sealed all those up earlier, they wouldn't be an issue.


















.


----------



## sgreer13 (May 17, 2014)

I agree, I think that I will thin the next coat. Actually my first two coats of finish went on with no bubbles, not to say that an imperfection in the previous layer didn't nucleate the bubbles in the top coat. I think the last coat was too thick. I appreciate everyone's suggestions.

~Mick


----------



## Al B Thayer (Dec 10, 2011)

Jim
Too many times we act like lemmings and just follow along with what the manufacturers want us to buy and use. While I realize poly is the hardest finish in the universe. It's by far not the best for so many applications. Not to mention difficult to apply and repair. Many times we think we have laid a perfectly flawless finish only to find when it dries you left with problems as you have described. 

One very overlooked product you can use that will improve the finish is turpentine. It's going to help the finish flow out better. Turp does leave some solids behind that also help the finish, min spirits don't. It's also not a petroleum product.

Also. Why not use any other finish instead of poly. I haven't got a table top in two houses with poly on them and they do quite well and look beautiful. 

Al

Nails only hold themselves.


----------



## jjrbus (Dec 6, 2009)

For starters I do not like to spray paint. I do not like the smell the mess the cleanup, nothing about it.

Then inexperience, I have not done that much over the years, nor have I been around people that do other finish's except spray lacquer.

I have only had minor problems with poly before, one time I had problems, but that was spraying it. 

So I guess it is time to experiment with something else? Next project, not this one.


Thanks JIm


----------



## Al B Thayer (Dec 10, 2011)

jjrbus said:


> For starters I do not like to spray paint. I do not like the smell the mess the cleanup, nothing about it.
> 
> Then inexperience, I have not done that much over the years, nor have I been around people that do other finish's except spray lacquer.
> 
> ...


Jim
I'm not an expert at many finishes. I was lucky enough to have an old guy teach/ show me a finish that has been my go to finish for almost all my furniture. I have a few for this and that and that's about it. I used poly one time and had trouble, didn't like the end result and went back to my old stand by tried and true. 

I didn't get into spraying finishes until I was forced to due to a large project that just wasn't going to work out without it. So I share your dislike for spraying. 

Al

Nails only hold themselves.


----------



## jjrbus (Dec 6, 2009)

Thanks for the response.

So what is the tried and true finish? JIm


----------



## Al B Thayer (Dec 10, 2011)

jjrbus said:


> Thanks for the response.
> 
> So what is the tried and true finish? JIm


It's a wipe on with a twist. Ignore the directions on the back of the can. I don't wipe on and wipe off excess with a rag. I just keep wiping on more and more finish and rub it out with my hands. My first coat is equal to three and its deep in the wood. 

I thin with Turp. It works better. Mineral spirits is another lie the industry has laid on us. It can also be left on the shelf for other uses like cleaning something.

Almost all finishes need to be rubbed out after they are built up. It makes it level and gives it the correct shine or sheen. None of my furniture was finished with satin or semi and none of them have a gloss finish. 

You can google these types of finishes and find the one that suits you. There is more than one way to skin a cat ....without poly.

Al

Nails only hold themselves.


----------



## punkin611 (Sep 17, 2013)

Well, here's my two cents worth. I have seen your problem before. IF you are using reclaimed wood, steel wool or any other possible contaminate you need to seal it in first. Dewaxed shellac first then your poly. Some time back I refinished a mahogany table top that had a old worn thru finish on it. I sanded it perfectly then I got in a hurry, I went straight to poly BIG mistake. Next day I went to see my handy work, what a shock! holes all over the finish as big as TWO in.! I mean no poly inside a two in. circle. I will never top coat with poly without dewaxed shellac under it. A added perk is a hundred years from now the guy who refinishes it will thank you.


----------



## Al B Thayer (Dec 10, 2011)

punkin611 said:


> Well, here's my two cents worth. I have seen your problem before. IF you are using reclaimed wood, steel wool or any other possible contaminate you need to seal it in first. Dewaxed shellac first then your poly. Some time back I refinished a mahogany table top that had a old worn thru finish on it. I sanded it perfectly then I got in a hurry, I went straight to poly BIG mistake. Next day I went to see my handy work, what a shock! holes all over the finish as big as TWO in.! I mean no poly inside a two in. circle. I will never top coat with poly without dewaxed shellac under it. A added perk is a hundred years from now the guy who refinishes it will thank you.


Some things are just not done. Mahogany and poly. Sorry the thought just boils my blood.

Al

Nails only hold themselves.


----------



## punkin611 (Sep 17, 2013)

Al B Thayer said:


> Some things are just not done. Mahogany and poly. Sorry the thought just boils my blood.
> 
> Al
> 
> Nails only hold themselves.


Please explain why you don't like poly on mahogany.


----------



## Al B Thayer (Dec 10, 2011)

punkin611 said:


> Please explain why you don't like poly on mahogany.


Poly on mahogany is tantamount to plastic slip covers on expensive living room furniture. Mahogany is wood chosen for the beauty of the wood grain and all possible options for obtaining it should be executed. If someone finished mahogany with poly they have lost half the beauty. Many times when finished the grain looks like a 3D hologram. It has depth and warmth. It looks rich like a good chocolate cake tastes. It's so smooth it feels soft.

Why use poly? If you need to protect the surface by arming it with a bionic covering. I'd say just get some coasters and teach the children the value and how to respect it. If you don't know of other finishes that would more than protect the wood. Look into some of the finishes written about in fine woodworking magazines or go on line and read about how to apply a varnish that makes the grain "pop".

Poly is a film finish that doesn't enhance the grain and color of the wood
Poly can be difficult to apply if humidity isn't conducive to it. 
It cracks and chips and is difficult to repair.
Poly works great on a floor, maybe a bar top.

Al

Nails only hold themselves.


----------



## jjrbus (Dec 6, 2009)

Interesting, I agree on the mahogany.

But I have not had problems repairing poly, just lucky, not enough experience?

On my cheap oak like substance desk, I removed the lacquer on the top and refinished it with poly. I abuse/beat it, sand it down and apply another coat. Good for a couple more years.
JIm


----------



## Brian T. (Dec 19, 2012)

Here's another possibility: the wood anatomy of oak and I'll bet a dime that your project was wood from some member of the "red oak" group of species.
The pores, the vessels which conduct water in the living tree are wide open from the roots to the leaves. Dry and in service in your project, those wood pores are air filled. Your finish simply displaced the air in the wood.

Red oak, such as for flooring, requires a pore sealer, made for the application. Once dry & set, the surface can be sanded back and the pores are invisibly filled. I'll raise my bet by a nickle and claim that the old desk got pore sealer.


----------



## Al B Thayer (Dec 10, 2011)

Good points on the oak wood.

I would encourage anyone finishing oak to seal the pores first as part of the finish schedule. It's a grainy wood and when all the open grain take on stain it loses the ability to be a fine finish. Just too much contrast between the color desired and what you end up with. And while many desire this grainy look. You may find others including the wives might need it toned down. It also this is really the only way to get a flat table top.

Al

Nails only hold themselves.


----------



## cabinetman (Jul 5, 2007)

Al B Thayer said:


> Good points on the oak wood.
> 
> I would encourage anyone finishing oak to seal the pores first as part of the finish schedule. It's a grainy wood and when all the open grain take on stain it loses the ability to be a fine finish. Just too much contrast between the color desired and what you end up with. And while many desire this grainy look. You may find others including the wives might need it toned down. It also this is really the only way to get a flat table top.


You certainly are entitled to your opinion. But, you infer that it's a fact and the only way. Some like wood finishes that have the look and feel of wood, where there is some dimension to the grain. It doesn't have to be slick like glass, or look like plastic. And, that finish can be achieved with lacquer, oil base varnish, waterbase polyurethane, conversion varnish, and of course oil base polyurethane.


















.


----------



## Al B Thayer (Dec 10, 2011)

cabinetman said:


> You certainly are entitled to your opinion. But, you infer that it's a fact and the only way. Some like wood finishes that have the look and feel of wood, where there is some dimension to the grain. It doesn't have to be slick like glass, or look like plastic. And, that finish can be achieved with lacquer, oil base varnish, waterbase polyurethane, conversion varnish, and of course oil base polyurethane.
> 
> 
> 
> ...


Thanky you Mr Buzzkillington

Nails only hold themselves.


----------



## cabinetman (Jul 5, 2007)

Al B Thayer said:


> Thanky you Mr Buzzkillington


You're welcome. Name calling ain't nice.


















.


----------



## Al B Thayer (Dec 10, 2011)

cabinetman said:


> You're welcome. Name calling ain't nice.
> 
> 
> 
> ...


You started it with your remark nobody needs. Whats with you anyway? I told the mods I'd play fare until you push my buttons. Your best bet is to not adversely quote and reply to me. In my book you've screwed the pooch on any kind of conversation with me here. Give up.

Al B Thayer

Nails only hold themselves.


----------



## cabinetman (Jul 5, 2007)

Al B Thayer said:


> You started it with your remark nobody needs. Whats with you anyway? I told the mods I'd play fare until you push my buttons. Your best bet is to not adversely quote and reply to me. In my book you've screwed the pooch on any kind of conversation with me here. Give up.


If you expect others to respect your opinion, then you have to accept the opinion of others whether they agree with you or not. If you can't do that without acting childish, maybe another forum would be better for you.


















.


----------



## Al B Thayer (Dec 10, 2011)

cabinetman said:


> If you expect others to respect your opinion, then you have to accept the opinion of others whether they agree with you or not. If you can't do that without acting childish, maybe another forum would be better for you.
> 
> 
> 
> ...


Wake up! it's not what you say it's how you say it. You and I have been round and round. Best off if you make your point with out a quote and the extra drivel towards me your so fond of. 

Thayer

Nails only hold themselves.


----------



## jjrbus (Dec 6, 2009)

An issue with the internet is the lack of facial expressions and body language and also tonal properties. Often causing negative interactions which occur often but are not necessary. 

I would hazard a guess that in person you would probably get along. I say this from experience as someone I know is a total obnoxious, jerk who constantly alienates people on the internet. And a great guy in person, go figure. 
JIm


----------



## Brian T. (Dec 19, 2012)

jjrbus: in the meantime, can we get back to the puzzle at hand?
I'm really curious about the wood.

If Al B and CabMn can't get along,
they aren't making a positive contribution to this thread.
Less than turds.

We know that.
"Breathe in, breathe out, move on" (thanks, Jimmy)


----------



## Al B Thayer (Dec 10, 2011)

Robson Valley said:


> jjrbus: in the meantime, can we get back to the puzzle at hand?
> I'm really curious about the wood.
> 
> If Al B and CabMn can't get along,
> ...


Oh you think your above reproach after that comment? Do you really think that comment is doing the situation any good? Did you think it would go without a reply from me?I have been contributing to the thread. Your a little late to the dance here.

Al

Nails only hold themselves.


----------



## Brian T. (Dec 19, 2012)

No, I'm tired. I am never above reproach. 
Yeah, I phuque up lots of times.
I refuse to aploooooooogize for pointing it out.

The situation is poisoned, I'm disappointed, that's all.
I want to know more about the oak finishing puzzle.


----------



## Steve Neul (Sep 2, 2011)

Robson Valley said:


> No, I'm tired. I am never above reproach.
> Yeah, I phuque up lots of times.
> I refuse to aploooooooogize for pointing it out.
> 
> ...


Bubbles in the finish has nothing to do with the wood. It had to do with how the finish is mixed or how it was applied. A lot of times you can create bubbles by over brushing it. The more a finish is brushed it gets air into it and sets up sometimes before it flows out and skims over with a bubble underneath. If the finish is starting to set up the bubble then doesn't have a chance to get out. Sometimes a bubble will pop and even leave a crater like a fisheye. If the finish is thinned enough it doesn't pull on the brush and you apply it as thin as possible with as few strokes as possible it shouldn't create bubbles.


----------



## sgreer13 (May 17, 2014)

Cabinetman and Al B Thayer

First one to stop by and refinish my coffee table wins the day ! ...I dont know what I would do if you both stopped by though.


----------



## cabinetman (Jul 5, 2007)

When questions are asked there comes a variety of answers. The person asking those questions have the option of which ones may be the cause of the problem. An example of how divergent answers can get, some answers aren't even addressed while others can be a continuous repetition of the same reasons. For the particular problem of this thread, in posts #4 and 16, I stated that from the photo, it appears that the bubbles follow a dark grain line, they aren't random bubbles. Finish gets drained into pores and leave a bubble. There could be other causes, but this answer was never addressed. Usually too much of an application will allow this to happen. If nobody likes this answer, that's fine, it's just my opinion, from my experience.

As for me 'arguing' with someone, it's not an argument on my part. It's usually a response to some method, process, or statement that I may disagree with. My responses are usually very polite, and to the point. I don't do any name calling or talk down to anyone. I find some members don't like it when someone disagrees with them. 


















.


----------



## Al B Thayer (Dec 10, 2011)

sgreer13 said:


> Cabinetman and Al B Thayer
> 
> First one to stop by and refinish my coffee table wins the day ! ...I dont know what I would do if you both stopped by though.



Hey I would love to but I don't do refinishing of any kind. Just never liked that kind of work. I would call on Neul. I trust his methods for refinishing over anyone here. He's always trying to help with the OP's question and has a wealth of knowledge on the subject.

We should go back and read the OPs question and answer in the context of that question, like Neul and some have. The OP was not off base and his ideas were not in poor practice. No one was going to lose a finger. 

Al

Nails only hold themselves.


----------



## knotscott (Nov 8, 2007)

Can we please keep the discussion civil and on track so we don't need to take more action on this thread? Potshots aren't necessary or helpful.


----------



## Road rider (Jan 29, 2012)

I agree with Steve


----------



## Al B Thayer (Dec 10, 2011)

wendell white said:


> I agree with Steve


Ditto

Al

Nails only hold themselves.


----------

