Fish eye bubbles in epoxy coating

Q: My builder was required to resand and recoat my timber floors with a full gloss epoxy coating. This is his third attempt due to what I believe are fish eyes appearing. I told the builder the biggest mistake he made was painting over silicone that was used around the base of the kitchen joinery.

With his third attempt at recoating he removed the silicone, but fish eyes reappeared and reappeared in different locations. He has now contaminated the entire floor area and cannot get a contaminate free finish. Do you agree with my assessment, and if so, what do you recommend he do to get a quality finish?

A: I’ve never used an epoxy coating on a wooden floor and can’t even imagine the nightmare of trying to do so. This is not a usual product to apply to a floor.

I agree with your assessment regarding the silicone. Nothing is going to adhere to that.

Fish eye bubbles are generally caused by air flow across the floor while applying the coating and not from contamination. This causes far too rapid evaporation of the solvent before the finish has even settled down. All windows and doors need to be closed initially.

Webmaster’s note: This reminds me of a question we got where the home owner had accidentally contaminated the floor job with over spray from the cleaners they used on the cabinets. This also involved fish eyes.

Will applying additional coats correct fish eye bubbles?

Q: We attempted to apply a top coat of polyurethane on our old floor with a roller. It is full of bubbles. Will applying additional coats correct this?

A: You will have to rub this coat down really well to knock off the bubbles, especially so if they are fish eye type. Some finishes roll on very well but you must make sure there is no air movement across the floor for several hours after applying the finish so that it doesn’t set up too quickly and allows the finish to flow out smoothly.

Similar Q: Why does our floor have bubbles between most of the floor boards, after it was recently refinished?

A: Is this just bubbles or actually beads of finish on board edges?

Bubbles can appear if the solvent is evaporating too quickly. This can happen, for example, if there is a sky light or a lot of window exposure with direct sun light heating the floor. Best to cover the windows while coating.

Fisheye and many rough spots after finishing

Q: We had our 48 yr. old oak floors refinished by a pro, sanded to bare wood and 3 coats of oil base satin poly. I complained that there were many very rough edges and swirl marks from the buffer, so the pro then buffed and did another coat of poly. This time with a different brand, Fabulon, oil also. (Not sure what brand the previous three coats were.)

While applying the 4th coat he started seeing what he called fisheye, spots where the finish didn’t adhere well. He buffed and did a 5th coat, not as bad, but still some fisheye and many rough spots. I don’t think he tacked with mineral spirits after buffing, would that help prevent fisheye? Should he use a finer screen to prevent swirls and rough spots? Thanks.

A: Everything we do when sanding and coating floors involves scratching the wood and the finishes to gain adhesion. The aim is to make such scratches fine enough that they are not visible from a standing position. I’m surprised you could see swirls through the satin. I wouldn’t use a screen any rougher than 180 grit when buffing between coats, and prefer to use even finer 220 when possible but that depends on how hard the previous coat is when I buff it. There are also newer abrasive pads created because of the swirl issue. 3M makes a maroon pad which can be used with 180 grit sanding strips and now Norton Abrasives has created a line of abrasive pads which promise not to leave such marks.

I always vacuum then wipe the floor down with a micro weave mop before coating. Wet or dry doesn’t matter. All air movement should be prevented after application so the finish will have time to smooth out before setting up.

Similar Q: Is there any other way to get rid of the tiny air bubbles in my floor besides another coat of poly? Can I sand them with 220 grit screen and then apply a wax to bring back the finish?

A: You will need to abrade the surface coating to knock down the bubbles and apply another finish coat. Make sure no air is moving across the floor while it sets up. I definitely would not recommend applying wax over this top coat. It will be very slippery and impossible to keep clean.

Finish eroding in a bubble-like pattern in some spots

Q: We have a four year old floor and around the fridge and some cabinets we have found places where the finish is eroding in a bubble-like pattern. We just had the whole floor refinished and that day the bubbles returned. They are not like air bubbles but are the same shape. What are they and how do I get rid of them?

A: My guess is that when the floor finish was applied the fan on the refrigerator started to blow air across the floor, causing these “fish eye” bubbles to form. The only thing that can be done is to rub them down with a fine abrasive and apply a fresh, thin coat of finish to the entire affected board.

Related Q: I hired a professional to refinish my red oak floors. He took them down to bare wood and used 3 coats of oil based Duraseal clear coat. Floors were beautiful. Then I came home to chicken pox like texture all through the floors. He says it just needs to cure. I have had floors done 2x throughout the years and have never seen this.

They are not air bubbles. They are visual. Will this go away? What caused it? How can it be fixed?

A: Sounds like perhaps fish eye bubbles. This happens when the solvent leaves the film to quickly, often from a breeze blowing across the finish or the sun shining through the windows and heating up the floor.

Is this fish eye bubbles or dust between the layers of poly?

Q: I have recently had my floating floors fully sanded back to bare wood then recoated with a base and 2 coats of poly. I have lots of bubbles all over the floor. He has since re-sanded lightly and recoated with another coat of poly, though this has only slightly improved the finish. To the eye there are ‘bits’ everywhere. I don’t know whether this is fish eye bubbles as you describe or dust between the layers. I am unhappy, but should I expect this kind of finish or should it be flawless?

A: Flawless? 🙂 Working in an open environment, I don’t think you can expect flawless. You can always expect an occasional fleck, pimple or bubble. That is a far cry from ‘lots of bubbles everywhere’. This could be caused by allowing air flow too soon after applying, using the wrong applicator which is injecting air into the finish, dirty finish or a contaminated environment, or even a problem with the finish itself.

Bubbles everywhere indicates a problem exists that needs to be corrected.

Similar Q: I had new oak floors laid after a water problem at Christmas. Today the 2nd and 3rd coats were applied and non one was in the house from 8am-8pm, just flooring guy. I came home to pimpling on floor, looks like acne! The flooring guy says this is normal and wear and tear will fix it. Is this a lie? Should I be worried or is this really OK?

A: It’s not unusual to get an occasional fleck in the finish when working in an open environment. Occasional fleck, perhaps a fiber coming loose from the roller or applicator. If a person does not clean the floor well, does not clean their finishes and has wind blowing across the floor you can get bubbles and pimples. So, I would definitely not call this normal. If my finish did this, I would want to know why.

Ripples and bare spots and bubbles

Q: I just puchased my first home, a 7 year old townhouse with hardwoods in the living room. The floors were in pretty good condition, but family convinced me to have them buffed and poly’d with a high gloss shine, as several of theirs had been done and came out beautiful. I went with the same person as they did, only I did not have them sanded, just buffed and glossed.

I’m extremely unhappy with the outcome. My floors now look like a pond on a windy day, with ripples and bare spots and bubbles. The guy claims the previous owners must have washed them with an oil/soap and the poly did not adhere to the surface (though he says everything “powdered up” as it should have during the buffing. He says now they need to be sanded and done over. I’ve already paid $250 for the buffing (a break because he’s been used by my family members) and he now tells me it will be another $400 to sand and refinish.

I can’t live with the floors they way they are, but my budget is growing tighter each week. Is it possible that his craftsmanship was simply poor? And should he be willing to lower this $400 cost? Or, should I just find someone else? I’m moving in this weekend and this is a huge setback for me and all the inconvenience this will cause me by needing to seal off other rooms and my freshly cleaned carpets, etc., as well as moving back in to my parents while the floors are being done.

A: Adhesion is the most significant issue. It may very well be that there was a contaminant on the surface. In this situation, I generally warn people that I will attempt to use a cleaner to remove any possible contaminant, but there is no guarantee. Ripples, bare spots and bubbles are another issue, but are irrelevant now given the adhesion issue.

They will need to be fully sanded and finished. I would suggest you try and find someone who incorporates some sort of vacuum/filtration with their sanding equipment so that dust isn’t an issue. I would consider such a company willing to invest in equipment like this to take their job very seriously.

Did cutting the poly cause this?

Q: I had problems with the third coat of poly drying too fast and leaving lots of bubbles. So, I hand sanded with 100 grit, and with the 4th coat decided to cut the fast dry poly with 25% mineral spirits to ensure no bubbles, and let it slow dry (no ventilation). Now I can see all the sanding marks on the floor? Did cutting the poly cause this?

A: 100 grit is far too rough to buff polyurethane. If you have access to a polisher, knock it down with 180-220 grit. I would almost bet you are using M****** polyurethane. If you want to use an amazing finish, contact and have him send you a gallon or 2 of Primero in whatever sheen you need. Note: Satin will tend to hide the sanding and other marks much better than gloss.

Follow-up Q: Thanks for the suggestion. You’re right on the M*****. The Big brand out there obviously. I must be prone to leaving bubbles. Unfortunately, I had to put my house back and will let the floor “wear in”. I learned tons on this project. From all the mistakes I learned from, I will be a pro refinisher on my next project. Great website, thanks.

A: M***** is a “big brand” for the home DIY person. Few if any professionals would use the stuff. You should do better next time around. I have to warn you though. This trade is so difficult and involved, it really requires an apprenticeship over a period of time to even become qualified enough to be left alone on a job. Good luck.

4th Coat and fish eye bubbles

Q: I sanded my floors, then put 2-3 coats of poly on them. I decided I wanted another coat-that was done about a month ago… fish eye bubbles all over the place now! I don’t want to have to rent another sander (it’s a huge fuss in an apartment building). This is a very small floor space. A pro tried to get rid of them by putting another coat of poly on-a colleague of his told him this might or might not work-it didn’t! I would love to get rid of the fish eyes for once and all.

A: I would let this coat dry for a month. Rent a polisher and use 180-220 grit screens to “grind” the finish and bubbles down. When applying top coats, it is best to make sure the environment is very clean, no air movement for several hours after application, and try to avoid direct sunlight hitting the finish….all this to prevent it from setting up too quickly.

A polisher doesn’t really make any more noise than a whooshing sound. It shouldn’t disturb anyone.

Follow-up Q: Since I might be doing this work myself, as opposed to hiring someone to do it for me, would you be able to tell me how heavy a polisher is to push on the floor, and what is a grit screen? The floor was very clean and the only air movement that took place was the air coming out of 2 windows-no fan was on or A/C. Could this have had anything to do with the amount of humidity of the air outside and/or the temperature outside? I would like to remedy this problem without spending a lot of money on doing so. Do you think letting this sit/dry for a month might do? The layer that got me the fish eyes was done about 2 weeks or so ago and then another layer of poly was put on that to hopefully remedy that one, about a week and a half ago. So, you think I just sit with it for another month?

A: Screen mesh abrasives are discs that are rated similar to sandpaper. the higher the number, the finer the abrasive. You don’t want to be buffing or scratching a fresh coat of polyurethane with a rough abrasive.

The factor humidity has with a typical omu is that the higher the humidity, the slower drying. However, air blowing across a fresh coat of finish can cause it to set too fast, and hence, not flow and level properly. Even the applicator used can be a factor. For example, a roller can tend to inject bubbles into the finish.

The reason I say to wait? You have how many coats of finish on the floor? 5? A typical finish cures by solvent evaporation. If you pile on too many coats, how can the solvent escape? You may end up with a very tender finish that stays soft for months because the solvents have been locked beneath the surface due to multiple coats. Let the coats you have fully harden, then try again.

Air bubbles

Q: I have just sanded doing the 36, 50, and 80 grit. I stained it as well. However, when I rolled the first coat of oil based polyurethane I got bubbles everywhere. Is there a way to get rid of the bubbles with out re-renting a buffer, etc.?

A: You can always strap on a good set of knee pads and rub the floor down with fine sandpaper or steel wool. Some finishes don’t roll well, and you may have injected air into the finish. Also, if it is too hot or too dry in the room, or if you have a lot of air movement across the floor initially, the finish may not have time to flow/level, so it will set up too fast. Bubbles can be one result. Also, make sure you stir, but don’t shake the can of finish.

DIY Air bubbles

Q: I sanded my hardwood floors and refinished them with 2 coats of polyurethane. I applied the finish with a paint roller. The associate at the home centre told me what caused the air bubbles that I had after I put the first coat on. I resanded and applied 2 coats of finish. I didn’t realise there were teeny, tiny air bubbles in areas of the floor. This is a big room (22′ x 24′) and it is a little much to hand sand and I surely don’t want to have to use a floor sander again. Is there help for the air bubble problem that is not labour intensive for me? Someone told me to have the floor professionally buffed. Will this solve my problem?

A: This floor will need to be well buffed to smooth out all the pimples, ensure adhesion and apply another coat. Not only would I have recommended a professional do the buff and recoat, but the entire job. This is not do it yourself work You may find it difficult to get someone willing to come in to do this re coat now. Who wants to step into someone else’s mess?

Similar Q: I applied two coats of poly (clear gloss )to my floors. Now I see bubbles. I think I didn’t let it dry between coats. Will applying a third coat solve my problem, or how do I solve it?

A: If the first coat wasn`t dry you wouldn`t have gotten bubbles. The finish would have wrinkled. Make sure there is no air moving across the floor until it has tacked over. That should allow the finish time to flow out. You will have to buff down the finish hard to remove or knock down the bubbles. Apply in thin coats. Air flow across the floor is the major culprit with bubbles.

Related Q: If I decide to live with the air bubbles I have (after applying three coats of oil based polyurethane) will they “open up” and end up worse? I also had bubbles in my second coat, but didn’t sand as it was enough doing the first coat.

A: If you didn’t sand between the second and third coats you may end up with a peeling finish due to poor adhesion.

“Tender coat”

Q: I am having multiple problems with my new hardwood floors. The floors are oak, natural poly finish. First off, My floors have scratched very easily despite waiting several weeks to walk on them, and using a vacuum made for hardwood floors. I have had other hardwood flooring installed in my home and never had this problem. I had them put another coat but this time there are the swirl marks everywhere as well as bubbles. There is also a bright yellow stain in the middle? It looks like it could be a stain under the finish. These floors are brand new. The company said they would come back again but they are stumped as to why the floors are scratching so easily and how to fix the swirl marks. It is a reputable company.

A: You haven’t told me the type of finish used, whether water or oil borne, but I will take a shot. Marking easily? If they have used a decent finish, it sounds like you have what could be called a tender coat. This situation happens when multiple coats are applied before allowing sufficient time for the previous coat to dry, regardless of the finish technology used. In the one case, the solvent, mineral spirits get locked in the finish and will take some time before a full cure is achieved. Likewise with water borne, a small solvent content and small water content get trapped and time is the cure (no pun intended) There are several things that can contribute to slow drying, including environmental factors such as temperature, ventilation, humidity. There shouldn’t be any contamination issues, since this is a new floor. Also, each finish has a recommended spread rate which should be followed. For example, if the spread rate was 500 sq. ft. per gallon, but it was applied at the rate of 2 gallons for 500 ft., it would likely take about 3 weeks for the finish to cure enough to allow a buff and coat.

Swirls are as old as floor sanding. The floor has to be scratched between coats when using oil borne finishes to attain adhesion of the coats of finish. With water borne, usually only a single buffing is needed after the first coat to knock off grain raise, since these finishes bond chemically when applied with a certain time frame. A maroon pad is all that is needed to buff this finish. The finer the abrasive the less likely these scratches will show. I would suggest using a maroon pad with sand paper strips no rougher than 180 grit. But since this finish appears to be too soft at present, I would leave it for a month and give it another go then. but I have no idea what the yellow stain is. That would lead me to think the finish is water borne. If these finishes are applied to heavily, it can turn yellow in those areas.
I hope this gives you some answers.

Open windows

Q: Could open windows and cold temperatures have caused peeling air bubbles?

A: It may have been a better idea to leave the windows closed in the actual room where the finish was applied. Air movement across the floor when first applied would cause it to set up too fast, and hence, not level out. Cold temperatures in the room could have a similar effect. The finish, being cold, won’t flow and level. What is he using to apply this? Is he following what is called the proper “spread rate”? That is, if coverage is about 500 sq. ft. per gallon, Is he getting about that distance, or only, say, half that? This coats are definitely better! It could be that when he picked at the finish it was still soft. It may not be peeling off, but it may be soft. If he has applied the coating heavier than what is recommended, it could takes several weeks at least before the finish really hardens enough to attempt another buff and coat. Solvent entrapment occurs and leads to a “tender” coat that marks easily.

I would suggest leaving the floor to fully harden. Then perhaps take another go at it. I would give it a good polish with 220 grit screen, make sure to clean up any and all dust and wipe it down before coating. Make sure the finish is also clean. Leave windows in the room closed until dry enough to walk on (though you can open windows in other areas of the house.) and make sure it is around 70-72F. Make sure the finish is inside the house overnight also, so it is not cold when trying to apply.

Minimizing air bubbles

Q: I have recently sanded, stained and varnished the floors. They Look really nice but the last coat has accumulated air bubbles. I was wondering if there is a quick and easy way for me to remove the top layer containing the air bubbles and re vanishing them. Or, is there any solution, like sprays or liquids to minimize the air bubbles to make them disappear?

A: The finish will have to be buffed again with a fine abrasive to knock off the tops of the air bubbles. These fish eyes are the worst kind. After a thorough clean up, make sure there is no air moving across the floor which would cause the finish to set up too fast before it has flowed out and levelled. There will be some air in the finish, likely from the applicator you are using, and it needs time to flow and allow the air to escape.

Related Q: We just had red oak floors installed throughout our home. They were stained and had 2 coats of semi-gloss finish. My concern is that you can feel rough spots when you rub your hand across the floor. Is this right?

A: You say the floor ‘feels’ rough when you run your hand across the floor. You don’t say it looks rough, i.e. debris or pimples/bubbles, etc. It could be simply the heavy grain of the wood which is much more porous than the rest of the board. At most you might at some point need an additional coat of finish, but from what you say I don’t think there is anything abnormal with your floor. Remember, this is not a Yamaha piano with multiple coats of lacquer so that it is smooth as glass. This is a floor which you walk on.

Follow-up Q: Thank you for responding to my question. You’re right, I didn’t say the floor looks rough, but it does. It looks like there are pimples scattered across it. Is this what they call fish eyes?

A: Fish eyes are raised bumps with a crater in the middle. The floor will need to be ‘screened’ down well and another coat applied. Make sure there is no air movement across the floor while it is being coated and for several hours thereafter.

Second Follow-up Q: If I decide to live with the air bubbles I have after applying three coats of oil based polyurethane will they “open up” and end up worse? I also had bubbles in my second coat but didn’t sand as it was enough doing the first coat. Thanks.

A: The bubbles won’t become worse on their own, but not buffing between coats is a bigger issue and it might be a serious one for adhesion.

Putting poly on floors

Q: What is the best way to put the poly on your floors? I keep getting fish eyes w/ a poly roller. How do I get rid of them, and make the finish look good?

A: I can already see part of your problem. This roller is injecting air into the finish. If it sets up before the air can escape, fish eyes are the result. You are going to have to buff off the fish eyes or scrape them out. You will have to buff the entire floor at any rate, or you won’t gain adhesion between coats. Make sure there is no air blowing across the floor for several hours after application. Use a lambs wool applicator.

Small bubbles on coats of finish

Q: What can I do on the final coat to help decrease the bubbling? These bubbles are very tiny some are pin heads, smaller than pepper corns. I am going to use a sanding screen on this last one, probably should have on the first coat instead of paper. Went through too many pieces.

A: Not sure what is going on here. If these were fish eye bubbles, I would suspect you have a breeze blowing across the floor and the finish is setting up too quickly.

If I give 2 coats and have the same problem with both, and am using the same batch of finish, I usually use a different finish for the third coat.

It is certainly possible there is something funky with the can of finish you are using. Good luck getting any help from the manufacturer.

I would buff the floor again with a 220 screen or maroon pad with 180 grit sanding strips. Wrap a damp towel around a push broom and give it the Zamboni wipe down after vacuuming. Make sure the floor is not wet before applying the coat. Make sure the finish is clean and the mop is clean. Close all windows in the room. No drafts for a couple of hours at least.