Air bubbles in epoxy. Where do they come from?

By Roderick Kabel

Many people using epoxy ask each other if this-or-that brand has a problem with air bubbles. It seems like there are a lot of problems out there with air bubbles in deep pour and in table top epoxy.

Here’s the long and short of it; inherently, epoxy containers (jugs) are filled by the (a) manufacturer and when it arrives at your doorstep, the epoxy has zero air bubbles. This holds true for every epoxy brand on the market.

So where do air bubbles come from in deep pour and table top epoxy? It comes from you, the user, 100% of the time. Sorry to say, but this is true. By either hyperdrive mixing or improper wood sealing (or not at all), the epoxy “brand” is not to blame.

The most common mistake made by users is mixing the two parts of epoxy too fast. Mixing epoxy is not rocket science but it does take a degree of patience and effort to get it right. Epoxy, weather a 1:1, 2:1 or other ratio, is like a cooking recipe. And just like any cooking recipe, mixing, folding, and whipping make the difference between a mousse, a macaron, and whipped cream.

Likewise, the utensil used to mix epoxy is just as important. There are times when a mixing stick is needed and times when a cordless drill with a paddle is needed.

Mainly though, most air bubble problems in epoxy come from the manner in which the epoxy was mixed. Was the epoxy mixed gently or whipped into a frenzy turning it cloudy white?

Key factors to a good recipe:

  • Always take the time to measure the epoxy A and B sides with a bucket/container that has measurements printed on the side
  • Begin mixing the resin and hardener slowly and keep an eye on how much air is getting into the epoxy. If you are getting lots of bubbles, you are going too fast
  • Use a slow speed on your drill and paddle. Turn the drill on reverse, this will not allow the mixing paddle to trap air bubbles in between the blades
  • Scrape down the sides of the mixing bucket with a paint stick. This gets any of the unmixed A or B side incorporated
  • After mixing for the appropriate time frame, pour the epoxy into a fresh clean bucket and mix again for a few minutes. This is insurance that all of the A and B sides are fully mixed

Remember, whipping cream is for yummy desserts. Not epoxy projects.

“Ya okay fine, but I mixed properly!”

Great! You mixed properly, did all the things right but are still seeing air bubbles coming from your epoxy after the pour, right? 

At this point there are a few things to consider. Is the wood slab or table top seal coated? Is the live edge sealed? Are bubbles coming from underneath the wood slab, and rolling up the live-edge? Is the table surface porous allowing air to vent?

These types of air bubbles are most commonly caused from off-gassing that naturally occur from wood, and porous table top substrate materials. Wood and table surfaces must be sealed appropriately with epoxy. We suggest the WiseBond™ Quick Set Seal for this.  

Likewise, any object to be embedded in epoxy should have voids filled with epoxy (if applicable) and objects must be “wetted” with epoxy prior to thick pouring. This eliminates the possibility of air escaping object voids and the wetting eliminates trapped surface air on the object, preventing micro bubbles.

With all of this in mind, we've specifically engineered WiseBond™ epoxy to have the optimal consistency to allow for bubble release. Our epoxy’s makeup is thin enough so that bubbles that form in the epoxy, can't effectively hold their spherical shape. They therefore basically break up and rise to the surface where they can then easily be torched away.   

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