When it comes to epoxy, one of the most common issues experienced by beginners is the formation of air bubbles within their finish. There are a variety of reasons why they can appear, but typically they will manifest during the flood coating portion of the epoxy project.
Thankfully, they're relatively easy to prevent and remove if spotted early on. In this article, we'll explain how to prevent air bubbles, why they form in the first place, and what you can do if your epoxy has already cured with them still in it.
What Causes Air Bubbles to Form in Resin?
In most cases, air bubbles form for one of two reasons:
Cause #1: The Substrate Was Porous and Not Prepared Properly.
Many materials used as substrates for epoxy resin are porous, which means they have tiny pockets of air throughout their surfaces. When epoxy resin is poured onto an unprepared porous substrate, the air inside these pockets is pushed out and attempts to surface. However, because epoxy is fairly viscous, the air can get trapped within the resin coating, appearing as a bubble.
How to Prevent It: Apply an Epoxy Seal Coat Before Your Flood Coat
This can be prevented almost entirely by apply a seal coat of epoxy to your surface prior to your flood coat.
A seal coat is a manually applied coating of a smaller resin batch that is thin enough to let the air through, thus releasing it from the porous surface. The pores are instead sealed or filled with epoxy resin. In our store, we have an excellent brush and mixing container suited for seal coat applications.
Applying a seal coat at the beginning of your project will greatly mitigate the likelihood of air bubbles forming during your flood coat.
Cause #2: The Epoxy Resin Wasn't Mixed Properly
Two-part epoxy resins are stored as separate components which have to be mixed together to cure. During mixing, it's possible to pull in air, which can induce the formation of air bubbles. This generally occurs when using too much force during manual mixing, or when using too high a speed (or too small a batch) during electric mixing.
How to Prevent It: Follow the Mixing Instructions, and Mix Carefully
To avoid this issue, make sure to follow the instructions of your chosen epoxy brand. For example, with our Primaloc Epoxy, we recommend not using a power drill for batches that are less than a gallon. We also suggest keeping the drill at the medium speed setting and only activating it once the mixing bit is fully submerged. Keeping the bit low in the container prevents you from avoid pulling in air.
It's also a good idea to scrape the sides of the container with a stir stick to prevent resin from adhering to them. This will ensure a cleaner blend for when you pour, so that your epoxy can fully cure without issue.
Techniques for Removing Air Bubbles in Cured Epoxy
There are two techniques for removing air bubbles from epoxy resin, determined by whether the epoxy has already cured or not.
Technique #1: For Uncured Epoxy, Use a Heat Gun or Torch
You can remove air bubbles as they form (or right after) by using a heat gun or torch. Simply hold the tool a few inches away from the resin surface and briefly move it over the finish, left to right, until you reach the end.
Make sure you don't linger for more than 1 second, as this can start to cause heat damage. If you're using a torch, be certain not to let the flame touch the resin. It should held at a distance of several inches, due to the extreme heat it generates.
Examine your finish carefully after you do a single pass, to see if you missed any air bubbles or if a few more have formed. If you see any, repeat the process to remove those as well.
This is the much easier method of removal, but can only be performed near the beginning of the curing phase, shortly after the flood coat has been poured.
Technique #2: For Cured Epoxy, Sand and Apply Acetone
Sometimes you make a mistake and either miss some air bubbles or forget to remove them during the application process. If this occurs, it becomes a lot more troublesome to remove them, yet notably, it's still possible.
The depth of the bubbles will determine how this plays out.
For Air Bubbles That Are at or Near the Surface:
- Begin by lightly sanding your surface.
- Using acetone, wipe the surface carefully, giving it 30 minutes afterward to fully evaporate.
- Apply a fresh epoxy seal coat. This will fill in the imperfections. Then wait 4 to 6 hours for it to partially cure.
- Finally, apply a fresh flood coat to your entire epoxy surface. Once this cures, it should look good as new.
For Air Bubbles That Are Deep Within the Epoxy Finish:
- Begin by heavily sanding down your epoxy finish. You need to reach the deepest air bubbles to clear them all out.
- Using acetone, wipe the surface carefully., giving it 30 minutes afterward to fully evaporate.
- Apply a fresh epoxy seal coat. Then wait 4 to 6 hours for it to partially cure.
- Finally, apply a fresh flood coat.
Make sure you follow these steps, and recoat the surface entirely. If you attempt to target individuals spots, you'll end up with an uneven finish.
Primaloc Epoxy: Premium Epoxy for Premium Results
When it comes to epoxy resin, Primaloc Epoxy gets the job done. Bubble prevention has never been easier than with our premium-grade epoxy resin, which features high performance in every category.
Epoxy resin can be beautiful, strong, and long-lasting—which is why you shouldn't compromise on quality. With Primaloc Epoxy Resin, you get the ultimate finish in durability and visual appeal.
Protect your surfaces by giving them a rock-solid epoxy finish. Choose strong. Choose reliable. Choose Primaloc.