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 150 grit sandpaper on an orbital sander or pole sander
. 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 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.