You may need to coat existing epoxy for reasons such as damages, poor application, to strengthen durability among others. So, yes! You can epoxy over epoxy.
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Reasons Why You might Want to Coat Existing Epoxy
Epoxy coating often involves certain levels of preparation and before coating could be created, two separate solutions need to be mixed. Epoxy is strong, tough and durable, why then would you possibly think of coating existing epoxy?
Even though epoxy is a durable product, it is not considered water-resistant. Repeated moist or wet conditions can cause deterioration over time which will affect durability. For this reason, you might want to consider coating the existing epoxy.
In buildings such as workshops or garages where heavy objects may fall on the floor or drag, it will also be reasonable to consider coating the existing epoxy floor. This is because even though the epoxy coating is tough and strong, there may come a time when it would not be able to withstand the strength or toughness of the heavy objects that are dropping on it. Epoxy is not indestructible. In order to repair or strengthen your flooring against further damage, you may reconsider coating the epoxy flooring.
Also, certain preparations or application mistakes may occur which may warrant coating existing epoxy. Mistakes such as poor preparation, incorrect stretching out epoxy, incorrect mixing, presence of moisture in concrete when applying the coating, temperature or humidity issues may cause issues like colour differences, the appearance of bubbles, delamination, the appearance of circles and poor adhesion.
In addition, you may consider coating an existing epoxy just to add levels of epoxy coating to thicken and further build up the surface. If your flooring is exposed to damage or more chemicals than normal, you may consider coating the existing epoxy. Also, in a situation whereby the concrete underneath your flooring is prone or exposed to cracking, coating a second or subsequent layer of epoxy may just be necessary.
When Can You Apply Epoxy over an Older Coating?
You can epoxy over an old coating when the old coating has lost its sheen. You have to properly prepare it for the new epoxy however; otherwise, the new epoxy would not adhere. Plan a multiple coat flooring system and wait a long while between coats allowing the epoxy to cure before applying the next coat to get a chemical bond. Renew the clear topcoat. This may be after many years of service in a busy garage where the clear top of an epoxy floor may soon start to show its age.
The preparation must include careful cleaning with grease-removing detergent to the thin oily layer that may have built up but maybe invisible. You will need to etch the surface to make it rough just enough to bond with the new coating. You will need to repair the holes and chips on the floor. Allow the repairs to cure for at least 60 days before recoating with epoxy; provided you use fresh mortar.
When not to Apply Epoxy over an Older Coating?
While you may want to apply epoxy over an old coating due to the reasons aforementioned, it is possible in other situations that the need to apply epoxy over epoxy will not do. In which case, you will need to start from scratch completely.
One of such situations is when the old or existing epoxy is peeling already or has started to delaminate. This type of situation may signal a more serious problem that adding another coat of epoxy may not resolve.
One other situation is when the existing coating is outrightly worn and this makes the concrete more visible than coating. Applying another coating of epoxy on such coating will not work properly. The case will be the same or worse if the existing epoxy has been painted over or some other type of floor sealant has been applied.
Steps to Apply Epoxy over Epoxy
The first thing you should keep in mind before proceeding to apply epoxy over old coating is to make sure that the surface of the existing epoxy is rough. This is to make sure of the successful bonding and to make the existing epoxy coating more conducive to the second one adhering to it. The ideal tool for this is a power sander, but a sander pole can also be used. Bear in mind that, however, you are trying to de-gloss the surface and not remove it. Don’t be too rough with it!
After sanding the surface, sweep away the dust and then vacuum the surface carefully and thoroughly. It is essential so that all dust particles are removed. To ensure a cleaner surface, add some methylated spirit onto a clean rag or towel. Use it to wipe the entire floor surface.
Step 1: Prepare The Surface
In preparing the surface, you will have to follow the above instructions in cleaning the surface to prepare it for coating. This is perhaps the most important step because, without proper and adequate preparation, the floor or surface could fail. You can use a power sander or sander pole as earlier suggested. Or grind with diamond grinding, which is the most popular and most flexible method of surface preparation. Or shot-blasting, milling or scarifying.
Step 2: Sweep And Clean The Floor
Step 3: Prime The Surface
Prime the surface or floor with a suitable epoxy primer. Remember that better adhesion is necessary for longer life; and to seal the substrate and reduce the risk of bubbles and gases in your final epoxy coat, priming the surface is of utmost importance. Priming also helps wastage of products as it helps to reduce the amount of product that will be required in the later stages. Prime the surface with epoxy primer. In cases whereby the applied primer gets absorbed quickly by the substrate, apply a second coat of primer on top of the first one. This is very common with dusty and soft cement-based floors.
Step 4: Fill All The Cracks
Fill all the cracks, holes with epoxy grout. You will need to eliminate all holes, dents and cracks in the surface before starting to coat. If the holes are large and deep, fill them up in advance with a fast-drying cement mortar before grinding and applying primer. Use epoxy filler for small holes and cracks to avoid them being visible after the primer has been applied.
Step 5: Apply The First Coat Of Epoxy Paint
The purpose of this is to help reveal the floor, how the substrate is holding up. Anywhere that still needs adjustment will be visible now. Fill those places with the first coat. Use an electric mixer to get a thorough mix.
Step 6: Do A Final Sanding And Filling
Do a final sanding and filling before applying the final epoxy floor paint. After 16-24 hours have passed and the first coat has been sufficiently dried, proceed to the next step. In cases whereby debris and dust have been trapped in the first coat, they will be visible now. You can then sand those areas to get rid of any mark that could spoil the final round. Use a vacuum cleaner to collect any dust and use epoxy thinner to wipe the remaining specks of dust.
Step 7: Apply The Final Coat
Apply the final coat! This should be the easiest step if you have followed the steps given above. Clean the surface and start to apply the final coat. You may as well apply the third coat to make the surface look perfect.
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While finding means to retain the durability, sheen, seamless renewal of a floor or surface, you can epoxy over epoxy. This will give a brand new look to the floor.