Bubble formation in epoxy coatings is more times than not the result of air expanding within a porous substrate and releasing into the freshly applied epoxy. To avoid this issue consider the following:
- Avoid applying epoxy on a surface that is being heated either by the sun or a conventional heater. When possible, wait till the substrate has stabilized in temperature or is in the process of cooling before applying epoxy.
The first coat of epoxy applied on raw wood should be very thin. Use a 1/8" foam roller and apply the epoxy at 1/2 fluid oz. per sq. ft. Some ultra-porous substrates may require a second seal coat. If a seal coat is applied too thick, persistent bubbles which are difficult to remove will result.
- Bubbles can also be present over a fully sealed substrate. These bubbles are the result of entrained air from mixing or the product of brushing or rolling. Most of the time these bubbles will pop naturally. Stubborn bubbles can be popped by lightly dragging a brush over the surface of the epoxy. A propane torch can be used judiciously by holding the flame 6-8" from the surface while moving quickly back and forth. Do not overwork the bubbles with the torch as scorching of the epoxy can occur.