Two questions that we are often asked is how to recoat or apply a new coat of epoxy to an older epoxy floor that has already cured and can you apply a clear coat to an older epoxy garage floor coating? If you’ve done a little bit of research on epoxy application, then you know how important floor preparation is. So let’s discuss how to determine if your floor qualifies for a recoat and then how to prep the floor before you do.
When can you apply epoxy over an older coating?
There are many examples of when you can apply a new coat of epoxy over an older cured coating. The most common of these are for people who had previously applied a color coat and now realize that they want the glossy looks and advantages of adding a clear coat.
Sometimes it’s as simple as someone who planned a multiple coat flooring system and waited too long between coats, allowing the epoxy to cure, before applying the next coat in order to get a chemical bond.
Another reason is to renew the clear top coat. After many years of service in a busy garage, the clear top coat of an epoxy floor can start to show its age. With the proper floor preparation, you can add another coat of clear and make the floor look brand new again.
And then finally, you may have an older existing coating that is showing wear from years of heavy traffic and getting thin. As long as the floor is not experiencing any delamination issues, many times you can recoat right over a worn epoxy floor to create a brand new looking finish.
As long as the existing garage floor coating is a 2-part resinous product such as epoxy, polyurea, polyaspartic, or polyurethane, then you should be able to apply an additional coat of a compatible product without issue. However, to be safe you should always consult with the manufacturer of the new coating first.
When not to apply epoxy over an older coat
If the existing epoxy floor coating is peeling up or showing other signs of delamination, then you do not want to epoxy over it. There are bigger issues at play here that are causing the delamination. Applying a new coat of epoxy over such a coating will only lead to more problems. A complete removal of the old coating by grinding would be required.
If the coating is fairly worn with more concrete showing through than there is epoxy, then you will want to start fresh by grinding the floor.
Do not attempt to apply epoxy over existing concrete sealers. These need to be removed first as epoxy will not adhere to them. Also, floor paint is not a good base for epoxy and needs to be removed as well.
How to prep epoxy for another coat
The key to applying a new coat is to mechanically rough up the surface of the older coat to create enough bite for the epoxy to adhere to it. There are a couple of ways to achieve this.
The first is to use 120 grit sandpaper on an orbital sander or pole sander like this one at Amazon
. What you are trying to do is rough up the surface, not remove it. The surface should look deglossed after sanding.
Once done, sweep up the heavy stuff and then vacuum the entire floor with a shop vac. Next, use denatured alcohol on a small towel and wipe down the entire surface. The denatured alcohol will remove all the fine dust particles, evaporate quickly, and make sure that the surface is clean.
The other option is to use a floor maintainer (buffer) with a 100 grit sanding screen. You can usually rent these fairly inexpensively from your local home improvement center. They should have the sanding screens to purchase as well.
This method will go faster than the pole sander and cover a lot of floor quickly if you have quite a bit of square feet to prep. Just remember to occasionally check the sanding screen for wear and to make sure it hasn’t clogged up. After you are done, vacuum the floor and use denatured alcohol as described with the sanding method.
If you have an older clear coat that you want to renew, then you will want to use 80 – 100 grit sandpaper or a 60 – 80 grit sanding screen first to actually remove a small layer of the coating. This will help to eliminate any deeper scratches and/or embedded dirt that has marred the finish.
Do the same if you have a worn coating that is adhered very well but has some spots where the coating has worn through to the concrete. The more aggressive grit will insure that the bare concrete will be prepped properly as well.
Floor prep such as this goes fairly quickly. Once you wipe down the floor with the denatured alcohol, your floor is ready for a new coat of epoxy or floor coating of your choice.
I just had Epoxy floor put down. They did not put clear coat sealer on. ( i was told in did not need it) and it was put down when it was very cold out ( in the 30″s) now its starting to peel up in two areas. the contractor said he would come back and patch it. How do i handle this
Hello John. What brand and type of epoxy was it? Also, was this a floor coating contractor or a general contractor?
Don’t know the name of the product the general contractor put it down
OK. That doesn’t help much, but it does explain some things. General contractors know little about garage floor epoxy and the proper application of it. Most think it’s just like paint when it isn’t. Many of the problems we hear about are from general contractors or painters who put down a single coat epoxy floor. Floor coating contractors are the experts. Epoxy cannot not be applied in temps below 50 degrees or it will not cure. If it is indeed epoxy, then they must have used an accelerator to get it to cure fast or they used a polyurea coating. If it’s peeling, then that means they did not prep the floor very well in order for the epoxy to penetrate well to achieve a mechanical bond. This is very important when dealing with fast curing coatings. It also means that you may have more epoxy peeling at a later date. Either way, floor prep sounds like the issue. Did they grind first? I suggest you find out what product they put down as well. Your best bet, however, would be to ask for a refund and then hire a floor coating contractor to do the work.
I’ve got a client that had someone else epoxy their patio and steps (fully exposed) and didn’t add any grit or sand so it’s basically an ice rink when water hits it.
My hope was to add another polyurethane top coat with shark grip mixed in, but with the sanding of the current top coat am I going to need to add another color coat to make everything look clean and smooth again?
The color is a very light grey and there is a clear coat over the top. I’m imagining as long as I don’t sand down to far it should be fine, just wanted to get your thoughts.
Thanks!
Hello Adam. Has the epoxy ambered yet? Even with a polyurethane clear coat on top the epoxy is going to yellow if applied outside. Epoxy is not intended for outdoors. There is no problem with sanding the clear to apply another coat with polymer grit this time. You are only roughing up the surface and not trying to sand through it. Even if you did reach the color coat, as long as you don’t sand through it you are still good to go.
Okay great! I did notice it had yellowed a little in a few spots and spoke with them about it. They are just worried about the slickness for now, thanks for the advice!
I recently added epoxy to my garage but I’m not happy with the grey color I added. I’m wanting to change the color. Do I have to strip the epoxy down to the cement? or can I sand it enough to remove some of the rough paint chips and gloss and add a new color paint?
Hello John. Just rough it up to degloss it and then wipe it down with denatured alcohol on a a microfiber pad. After that you can apply a new coat.
Shea-
I recently applied my epoxy after grinding and priming the floor. I tried to avoid air bubbles by mixing the resin and hardener by hand, 90% of the floor looks great, but I ended up with soft/uncured areas, likely from the unmixed sides/bottom of the buckets when I poured them out. It’s been 6 days so I started hand scraping the soft areas out and wiping them off with xylol. I plan on sanding the whole floor with 100 grit sanding screen and doing an alcohol wipe before applying a new topcoat. The result of scraping has left low spots, should I fill those in with epoxy filler? Am I doing this right? Any other suggestions before I try this again?
Hello Aarin. Are you reapplying a clear coat or color coat?
Color with flakes then I planned on doing a clear urethane if it cures this time
OK, you are on the right track Aarin. You didn’t mention what type of epoxy or solids content. However, as long as it’s not a low solids epoxy, you can apply it thicker in the low spots to help level things out. If you scraped the sides of your mixing bucket while pouring the last contents out, then that is most likely the source for the uncured epoxy.
100% solids, and thanks again for the guidance!!!
Hi, I did garage floor, Contractor said its solvent based epoxy. Contractor did 3 car garage in less than 2 hrs, he also filled the cracks and immediately after that did epoxy . He did just cleaned the floor from broom and never washed it. Not sure if this is the correct way however he was confident that Epoxy will stay for 6 years. he also charged under $700.
Hi Nits. All concrete should be prepped by etching or grinding. If no prep was done, then the epoxy is going to fail and peel prematurely.
Hi, my neighbor who claimed to be an epoxy expert used rust oleum epoxy kit in gray. My garage floor is painted concrete and fairly new, house only 5 yrs old. He washed it and used the acid etch, left it to dry and the next day painted epoxy when it was about 90 degrees outside. It has now dried 3 days later and half the floor is light gray with a flat finish and half is dark and glossy. It was a 2.5 car garage kit for a 3 garage garage space and he said he mixed everything well. We can’t figure out why it did this. He thinks putting clear gloss over will fix it. I don’t think so. Do you think we can sand over it and use the alcohol as you mentioned above and try painting again? Do I need to remove it to start over? It looks pretty bad color and texture wise. Do you think it’s his error or the epoxy paint?
Hello Christina. No, applying a clear is not going to fix the problem. What happened is that the epoxy coating was stretched further than the coverage rate. A 2.5 car kit will cover UP TO 500 square feet. That’s if all conditions are right. Most of the time it’s 450 – 475 square feet. A three car garage is generally a minimum of 600 square feet. When this happens, the epoxy goes on much too thin which reduces color richness and leaves a matte finish. The only way to fix it is too apply another color coat and paying attention to the coverage rates.
Thank you so much. After sharing your comments with him and calling rust oleum for detailed instructions. I let him do it again. We bought 2 kits (2.5 car and 1 car), he mixed all the bases then separated them back out to activate one at a time. First he sanded with a 60-80 bit hand blaster to rough up the areas. Finally Florida weather agreed with us yesterday and we had low humidity and no rain! I bought a humidity monitor to be safe this time. It’s currently been drying for 19 hours! I’m a little nervous bc at 2am-9am this morning (it’s currently 7:33am) the humidity is 90 (above the 85 required) but this is 12 hours after installation and after 9am it will drastically drop to 80, then 70-60’s for the rest of the day. Should I be worried????
Last question, if it looks good – I’ve been to afraid to look, I’ve read your blog about why a clear coat is important, honestly I like the matte look and not glossy (I know I’m crazy) but you made a good point as to why from a longevity standpoint. Is there a gloss I can add as a protective shield that won’t be super shiny but still accomplish my goals? I used the 2 part epoxy shield from rust oleum. Thank you so much!
You should be good regarding the humidity, Christina. If it was over 85 the first few hours of the application, then you would have a problem. Clear coatings are glossy for a variety of reasons, one of which is that the gloss provides better wear and scratch protection. That is why it’s difficult to find a satin finish clear for a garage floor. The newer water-based polyurethane clear coats have more of a satin finish, however. You can find an example here. You won’t find specialty coatings like this from a home improvement center. They are more expensive than what you have put down already and it will require that you rough up the surface of the coating before application since you would be past the recoat window. The other option would be to apply a Rust-Oleum clear and then you could wax it to bring down the shine. The one issue with that is that it will require maintenance for the wax and it will not stand up very well to petroleum products.
Hi – I also recently used a RustOleum 2.5 garage car kit to epoxy my two-car garage floor. Unfortunately, the result is a kind of two-toned surface, instead a smooth grey. It hasn’t even been 24 hours yet.
I’m sure I need to put another coat down. Do I need to prep the first coat in any way, so the second coat goes down well? I was planning on buying another RustOleum 2.5 garage kit.
Advice would be much appreciated.
Thanks.
Hello Eric. Was it a Rust-Oleum epoxy kit or Rust-Oleum polycuramine? You have 48 hours with the epoxy kits to apply another coat and up to 7 days with the polycuramine kits (RockSolid). After that, you will need to prep the surface as we describe in this article. Also, I suggest you read this article here about how to ensure even color match for the whole floor.
Hi Shea,
My garage floor was epoxy painted when we built our house 17 years ago. It is really showing its wear and tear and something I probably should have addressed a few years ago. So…… there is more good than bad, however there are exposed spots/patches of concrete in quite a few areas. The thought would be to rent a commercial buffer with a 80 grit sanding screen. Then clean and use alcohol as you mention in your article. So what I am unsure of is what product is the best/most economical for me to use to coat over the old product. The original product that was used was a Scott-Tile Industrial Epoxy Coating Hi Gloss Finish…….918 parts A and B which is no longer available. So I am looking for options on what to use. Your suggestions would be appreciated. Thank you!
Hello Lee. There are quite a few options of garage floor coatings to choose from these days. If you want something that is going to last, then stay away from the home improvement store DIY epoxy kits. You may want to read this article about the choosing the best epoxy coatings. In addition, one particular product that we highly recommend for most DIY garage floors projects that demand quality performance is single-part polyurea. These articles may help you to get a better idea of what direction you may want to go. Once you do that, please check back if you have any specific questions.
I recently applied a Rustoleum rock solid metallic product on my new garage floor. After everything dried, I then applied the Rustoleum clear coat to the garage floor. Most of the floor cured properly but there is a section of the floor that did not and is still tacky to the touch. Is there any product that I can use to remove the clear top coat without damaging the epoxy coating? If I am able to remove the clear coat, do I need to do anything to the epoxy floor prior to adding another clear coat?
Hello Sam. How long has the clear coat been down?
The clear coat has been down for a week now and it is still tacky to the touch in the one area. The rest of the garage cured without any problems.
What you will need to do, Sam, is scrape up the soft area with a wide blade putty knife and then wipe it down with denatured alcohol to remove any residue. The surface that will get the recoat should be sanded with 150 sandpaper, vacuumed, and then another wipe down. After that you can apply the clear to that area only. You may want to give Rust-Oleum Customer Service a call to tell them your issue. They are known for assisting with discounts and even free kits to solve problems.
Thank you for all the help. Do you recommend using any type of paint thinner or mineral solvents in order to remove the top coat? Or is it best to just use the denatured alcohol?
You need to scrape up as much of the soft top coat that you can first. The denatured alcohol is to remove any remaining residue. Acetone or mineral spirits is a bit stronger, but it can leave a film. Make sure to do a final wipe with denatured alcohol to remove any films.
We recently got epoxy done. However, the epoxy never cured and 3 weeks into it is still wet and tacky. We used Rustolem epoxy shield dark blue. Our contractor is insisting on using a paint to harden the surface and reapply epoxy which I don’t think is the right course of action. As I read in the earlier post it should be properly sanded and not painted. Am I being paranoid?
Hi Kriti. You suspicion is correct, do not let them do that! You will have just have a bigger problem than you do now. If the epoxy has not cured then it never will. This is usually a result of the epoxy parts being mixed incorrectly and not allowing the chemical reaction which starts the curing process to occur. Epoxy does not dry like paint. It is a thermosetting resin that chemically cures. Applying paint over it will not create the chemical reaction and all you will have is a soft squishy coating with dried paint on top. Unfortunately, when this happens the epoxy needs to be scraped up off the concrete and all the residue cleaned off before a reapplication of epoxy can begin. Our guess is that a general contractor or painter attempted the epoxy application? Unfortunately, we hear of more problems when this is done. Most think applying epoxy to concrete is like painting a wall and assume they know everything. Floor coatings is actually a separate specialty among contractors. We feel for the issue they have caused.
Thank you for your confirmation. I also reached out to the company that supplied the product who suggested that if the epoxy hasn’t cured and is tacky we could apply another coat on top of it. Unfortunately, it’s so hard to get contractors to do this now because they think they know it all. I do not want this to be an experiment in my garage! Can you also help me figure out what is best way to scrape this thing off the floor. Some of it is wet but most of it is just tacky.
If you want to find someone who can get the job done right, I recommend you read our article on how to find a floor coating contractor. These are the experts who specialize in the field and know what they are doing. The best way to scrape it up is to use a long handled floor scraper. Something like this is an example. Once it’s all scraped up the concrete should be wiped down with MEK or acetone in order to clean up the residue.
Shea, I am a painter and recently re-painted a homeowners floor with Sherwin Williams latex epoxy. The homeowner isn’t sure what was used last time but he’s sure it was a sort of epoxy and overall the floor was in good shape before we painted. Simply had gotten dirty and all and he wanted a new fresh coat. What was on there before was latex as well according to my rep. We washed it, scraped, let it dry and applied the epoxy. A couple of weeks after, the homeowner called me to tell me that the epoxy we put down was peeling only with one of the cars while the other two garages floors are fine. I showed the problem to my rep and he says I need to grind everything down to bare concrete just to be safe and restart but I feel like there’s another solution perhaps. Not sure what you think? Also, I have a different homeowner who just called me to redo his garage floors and currently has a 10 year old epoxy on it also a little beat up but no major peels. Is it necessary to check for water or oil of what’s on there now? or will grinding the current product that’s on their allow me to use whichever epoxy product I want? Thanks!
Hello Victor. What was the exact name of the product? I ask because a latex epoxy sounds like a 1-part epoxy paint. 1-part epoxy paint is just latex acrylic paint fortified with a little bit of epoxy. This article here explains the differences. If it was a 1-part epoxy paint, then that explains the issues with the hot tire pickup. We do not recommend such product for a garage unless you are looking for a budget paint that you can just re-paint the garage floor with once a year or so. If you are using Sherwin Williams products, I would highly recommend ArmorSeal 1000. It’s a high solids epoxy that is not going to have issues with the hot tire pickup and peeling if the floor is prepped correctly.
In terms of the other garage; if the epoxy has been down for 10 years without peeling, then it definitely had a quality epoxy applied (not paint). All you need to do for prep is rough up the surface with 120 grit sandpaper or a use a floor buffer with 100 grit sanding screen. Wipe it down with denatured alcohol after cleanup and you are ready to go.
So the product I used is an H&C water based expoxy. It technically does come in 2 parts and you mix it together. Regardless it is the cheapest option Sherwin Williams has and I probably won’t use it anymore. Also if I use the armor seal can I put that on top of what’s on there now or would I have to strip off the h&c that is peeling up?
And for the second garage would you recommend me using the armor seal as well?
Thanks!
Yes, you definitely want to remove the H&C epoxy that is peeling up. If you don’t, then anything you apply over it will peel up with the H&C coating. We do recommend the ArmorSeal for the second garage or you will experience the same issues as the first garage at some point.
And what would be the best way to remove it? Grinding it or simply sanding it as much as possible?
Grinding is the fastest and most preferred method to get to bare concrete. However, if you just want to remove the upper layers of a poor coating to get to a base coating that is sound, then a floor maintainer with 60-80 grit sand screen works well.
I have a Rock Hard epoxy floor that I did about 6-7 years ago. The floor is holding up well but has yellowed and not the light blue it once was. What can I do to get it back to looking close to new again? Thank you.
Hello J. What your floor has experienced is a permanent condition called ambering. Epoxy is not U.V. stable and will develop a yellow (amber) tint over time if it is exposed to strong indirect sunlight. It happens much quicker if it’s exposed to direct sunlight. The only thing you can do is to prep the surface as described in the article and apply a new coat. Polyurethane and polyurea are coatings that are U.V. stable and do not amber. You may want to take a look at DuraGrade Concrete by Rust Bullet. It’s available in a light blue and will not amber.
Hi. Just got my garaged floors redone and I decided to use the epoxy clear to seal everything. It has cured nicely, but I noticed some streaking and that some areas are much thicker and more “wet” than other areas. Its very annoying to the eyes. Is there a way that I can even out the clear? Possibly so a slight degloss and sand to a semi gloss/satin?
Hello Don. From your description, it sounds like it was applied with a heavier application in some areas and not enough in others. One thing you cannot do with concrete coatings is stretch them out like paint. This can cause streaking as well as a duller looking coat in those areas. You cant degloss and sand coating to satin finish. The minute you start taking sandpaper to the surface, it deglosses immediately to a whitish haze. If you want to fix it, it will require roughing up and deglossing the surface with 120-150 grit sandpaper and then recoating.
After I degloss and rough it up with sand paper, I would have to clean up the debris and use denatured alcohol for prep before reacting correct?
That’s right, Don. A thick microfiber pad on a mop head makes quick work of it. Once done, the floor should be dry and ready to go within a few minutes.
Awesome. One last question. Since the clear is brand new and haven’t seen any traffic, I feel like sanding the whole garage would be a waste of money. I still have extra clear. Could I just sand off the specific section, wipe with alcohol, and reclear?
You can always do that, Don, but it’s not recommended. The reason is that coatings do not blend together like paint does on a wall. You will have definitive roller overlap marks where the new coating terminates over the older coating. This why it’s always important to keep a wet edge and why floors are not done one half at a time unless there is a natural border to use such as a contraction joint.
Hello,
I live in California, so Denatured Alcohol is not sold here and has not for several years. What be the next best product to wipe the epoxy down with before recoating? (It has already been sanded and vacuumed). Thank you in advance for your help.
Cheers!
G
Hey G-Factor. I thought you were misinformed at first, but was surprised to learn this was the case. We live in SoCal and just bought 2 1/2 gallon cans of Kleen Strip denatured alcohol in September from our local Home Depot. Checking back with the same store, they no longer have it. After researching this, apparently stores were allowed to sell what was left of inventory. Mineral Spirits will work in its place.
Thanks for the info, BUT Mineral Spirits has been banned in So Cal since 2011.
The State of California banned certain chemicals that used to be popular for many purposes. Within that, the South Coast Air Quality Management District (SCAQMD) has imposed even further restrictions, banning additional chemicals from most of Los Angeles, Orange, Riverside, and San Bernardino Counties. They add to the list of banned chemicals from time to time, too.
San Diego and Ventura Counties are not affected by the SCAQMD restrictions, but they are subject to California rules.
So no Mineral Spirits or Denatured Alcohol out in the Palm Springs area where I am (Riverside County). Looks like I need to make my annual trip over to Arizona to stock up. Thanks for the info.
Cheers,
G
Hey G-Factor. Home Depot actually carries a CARB compliant low odor version of mineral spirits. Here is the link. I should have posted that originally.
Hi all.
Have a garage floor finished with a 2 part epoxy. Lady doesn’t like the colour anymore.
Have sanded and cleaned.
Do I have to put another 2 epoxy down? Lady doesn’t want to wait for it to finish. Is there anything else I can put over the top that will stick but dry/cure quickly.
Thanks in advance
Stephen
Hello Stephen. If she wants a product that is not going to peel from hot tires and wear out within a year, then a quality 2-part epoxy or similar coating is required. We do not recommend paint or 1-part epoxy as it will be much inferior to what she has now. You could apply a 2-part polyurea coating. They can be driven on the next day, but they have a very short pot life (20 minutes or less) and require at least two people to get it down on time. These are usually applied by professional coating contractors.
Hi Shea,
I have a 2part solvent based epoxy floor that Is 3 months old and I have come to not like the colour.
The colour I like is in a water based epoxy.
Can I lay down the water based epoxy over the existing solvent based layer?
Thank you,
Craig.
Hello Craig. Yes, you can do that. What color and exact product are you thinking of using? I ask because most water-based epoxy coatings are not as durable as solvent based. Maybe we can make suggestion for something similar in quality to what you currently have with the color you want.
great site , thank you! i have a small area one square of a garage floor 10×10 that has battery acid leaks that has changed the color , i no longer have the golf cart that dripped on the epoxy floor , i had it professionally resurfaced a year ago and they did a fair job, the trauma was after their work, i would like to try this on my own , your site was the only site that gave some info, my floor is beige with full casting in a semi gloss, the damage is on one square , could you help me with some detailed instructions ?
Hello Berry. Is your intent to try and fix this one area or did you want to do recoat the entire floor? Are you referring to color flakes when you say a full casting? I’m assuming a clear coat was used? If so, what type? Epoxy, polyurea, polyurethane or?
I thank you for helping me, the garage floor is fine the one square is damaged with a yellow stains, i wish to redcoat the one square only, I realise the sheen will be close but not exact, yes the full casting is the amount of flakes, the epoxy is in very good condition, the way I would describe the beige has yellow stains, in the 10×10 square there’s less than a 5×5 damage,
Hi Berry. If you have full flake coverage, then you should not be able to see the color coat (beige) underneath. The flakes completely cover the color coat and then the flakes are coated with a clear coat. Is this what you have? Or do you have a beige floor with heavy flakes (not full coverage) and no clear coat?
Yes, sorry I did not fully answer your question, it is beige with heavy flakes , it appears to be a clear urethane over epoxy
OK, that helps. The discolor should be in the clear coat then and not in the epoxy base coat color. I’m assuming that the 10’x10′ square you are referring to is created by contraction joints in the slab? If so, then that helps quite a bit. Coatings (even clear) applied over older coatings do not blend well like touch-up paint on a wall. The overlap of the new over the old is obvious. A natural border such as a joint does a great job of avoiding this. You will need to sand the 10’x10′ square with 120 sandpaper to degloss and rough up the surface to accept a new clear coat. The smaller 5’x5′ area may need heavier sanding with 60 grit to get through the discoloration. A pole sander works fine, it’s just more labor intensive. However, a floor buffer with a 60 grit sanding screen will make the process easier and faster. Plus, it will make sanding out the discoloration easier. Once the sanding is done, vacuum the surface and then wipe it down with denatured alcohol applied liberally to a microfiber pad. This will collect the rest of the dust and remove any leftover gloss. You can then apply a new coat of the same or similar clear coat. Make sure to tape off the other side of the contraction joints when applying it.
correct the 10×10 is an expansion joint, i will go and rent a floor polisher/buffer/sander from the home depot with a disc with as close as you instructed, i have used an orbit sander with 220 while i waited for some knowledge it appears to be on the right track so now i will follow your guidlines, thank you very, very much for your knowledge
Hi, I’m in the process of prepping my basement floor for epoxy paint. The floor is currently painted with latex paint. It’s in very good shape, no peeling or bubbling. The concrete itself is not completely smooth, it has some texture to it – it looks like it was lightly brushed with a bristle broom before it dried. I was hoping I could just give it a good cleaning before applying the epoxy, not sure it even needs to be etched given it has some texture already. I’ve been reading conflicting information online, some say it’s ok to use epoxy over latex, some say the epoxy will cause the latex to peel and it will create a big mess. Should the paint be removed before I use epoxy?
Hello Julie. Are you planning to apply an actual 2-part epoxy coating or a 1-part epoxy paint? There is a big difference between the two.
The 2-part.
OK, that helps. As long as the epoxy is water-based it can be applied over the latex paint. Solvent-based epoxy can cause the latex paint to soften. You will need to rough up the surface of the paint before you apply it. If you don’t, then the epoxy can peel up off the paint. You can’t do it by etching though. Etching only works on bare concrete. Since the surface is a bit rough, the easiest method would be to use a floor maintainer with a green scrub pad. Go over it enough to take the gloss out of the paint. Don’t wipe it down with denatured alcohol. Instead, use clean water on a microfiber pad.
Thank you so much, Shea! This is very helpful!
I recently did a front porch with Seal Krete epoxy seal concrete and garage floor paint. Says it is an acrylic epoxy and states for exterior use as well. I used a Grinder on the concrete porch to remove many layers of built up paint as best as possible to prevent scarring the cement and sanded the rest with 60 grit sandpaper. A painter friend of mine said I should prime it first, so I did with a concrete primer. The epoxy went on very well, placed two coats and it looked great. My problem is, now that I’m using it, anything wet leaves water stains. I’m not sure where I went wrong? It didn’t say, but was I supposed to seal it with something? To correct this, should I sand it with a high grit and reapply. It will have to sit through the winter at this point. I just don’t want it to happen again. Thanks so much for these posts and answers!
Hi Sean. Seal Krete is not a true 2-part epoxy coating. It’s 1-part epoxy paint which is basically acrylic paint with a little bit of epoxy resin added to increase the durability. This article here explains the difference. It’s not uncommon for water to spot on acrylic paint. Sometimes it will clean up with a little scrubbing and mild soap solution with some vinegar added if you have tried something like that. Applying a new coat is not going to prevent it from happening again. These type of paints aren’t a true sealer either. You do have the option of applying a clear water-based acrylic coating over the paint if you like. It will resist water spots better and add some gloss. All that is required is to lightly sand the surface with 150 grit sandpaper before you apply it.
Thanks so much for that explanation, Shea. I will consider the top-coating.
Is there a proper paint/sealant I can put over this after sanding it or would it require stripping and starting again?
Hi Sean. The clear acrylic coating is a sealer. To actually seal the concrete with a color coat, it would require removing the paint to get to the bare concrete first. You would then apply a true coating. A true 2-part epoxy coating will amber (yellow/brownish tint) though if exposed to U.V. rays. You would need to use something as U.V. stable such as this product by Rust Bullet.
Ok. Thanks for all your help for us DIYers!
I had a floor that I coated with a two part rustoluom kit approx 8 years ago. It is doing well, plan to redo and want to add additional flakes etc. The first application seemed to fill some of the surface cracks, which are very small, but some of the others remained and showed through the epoxy. Any suggestions like filling the small cracks or should the additional coat fill them?
Hi Daniel. The reason it did not fill all the cracks is because the epoxy is not 100% solids. Since it’s a much lower solids epoxy (53% for water-based), the remaining 47% evaporates out in water. This evaporation of the water causes the wet film thickness to shrink by almost half. When this happens, the small cracks that were originally filled in by the wet coating are exposed as the coating shrinks in thickness. Applying another coat may or may not cover the rest. If you want to ensure that cracks do not show, we recommend filling them first with some Rust-Oleum Concrete Patch and Repair. You can usually find it at your local home improvement center or here at Amazon. Once applied and cured, you will need to grind it flush with the rest of the floor for a smooth transition that does not show through the coating.
I just finished a 2300 sq ft, 3 coat epoxy floor. 1st coat was a water based epoxy used as a prime coat (290 sq ft per gallon) 2nd coat was 100% solids epoxy that was finished out very smooth and glossy (330 sq ft per gallon) Third coat was polyurethane (460 sq ft per gallon, it rolled out smooth and the finish result looked fantastic and glossy. I went and checked on it about two hours later and the surface now has millions of micro bubbles in it every where. It actually looks like I put a heavy grit sand in the mix. The gloss finish is still there but the micro bubbles are unmistakable, the bubbles are pin head size and appear similar to tapioca pudding. The 2nd coat and Top Coat were applied exactly 24 hours after the previous coat and the epoxy was still soft and not fully cured. Air temp all three days was 68, 72, 61 degrees. Slab temp all three days measured 62 degrees with infrared thermo. Shop is insulated and sealed and temp doesnt drop below 60 degrees at night. Floor was prepped with 36 hours of grinding by three different machines to get a smooth porous floor. I have just over 50 hours invested and im disappointed that all the hard work resulted in a undesirable finish. Id consider re-sanding top coat and applying another poly top coat but Im not interested in spending the time or money and end up with the same results. I have no idea what went wrong.
Hello Kirk. The epoxy should not have been soft before applying the next coat. It should have been hard enough before applying the polyurethane that if you pressed your thumb to the surface it would not leave a print. If you peel the skin off the top of one of the bubbles is there a hole at the bottom? If so, then that is a sign of off gassing from the slab that has come through the entire coating while it was curing. However, if after examining a few bubbles and you don’t find any holes at the bottom, then it’s the polyurethane that bubbled. This can happen from a few things. One is aggressive mixing of a 2-part polyurethane. It will introduce air into the coating that forms bubbles after it has been applied. Another and more common reason is from applying the polyurethane too thick. It needs to go down thin or bubbles will form. If the issue is only with the polyurethane, then you can recoat it to fix the issue. It requires sanding the entire surface and removing just enough of the coating to remove the top layer of bubbles to open them up. You can then apply a new thin coat. This will fill the small holes the bubbles created and make them disappear.