Bubble formation and elimination can be a problem with solvent-free epoxy coatings, like System Three® SilverTip™ and Mirrorcoat®, especially when applying to porous surfaces like wood or concrete. The cause is typically due to either one of two things:
1) Air expanding within the substrate and releasing into the freshly applied epoxy, or
2) Air entrained in the mixed product during mixing and applying.
Suggestions to avoid trapping bubbles:
- Apply the epoxy on a surface that is in the process of cooling down or at least at a stable temperature. If the material is being warmed by the sun or another heat source, air will expand and come out of the material forming bubbles in the epoxy coating.
On the bare substrate apply an initial, very thin coat to seal in any air pockets in the material. On a flat or broad surface, use a 1/8" nap foam roller and apply the epoxy at 1/2 fluid oz. per sq. ft. Some ultra-porous substrates may require a second coat to fully seal in air pockets. If bubbles still form, dragging a disposable bristle brush across the wet epoxy should remove them.
On irregular surfaces, use the bristle brush and brush out the coating just thinly enough to wet the surface. If any one epoxy coat is applied too thickly, the air pockets will expand and form bubbles which will become trapped in the epoxy.
- Even with a fully sealed substrate, bubbles can persist in subsequently applied epoxy coats. These bubbles are the result of entrained air from mixing the material before application. Usually, these bubbles will pop by themselves before the product has gelled. Stubborn bubbles can be removed using a propane torch, waving it back and forth holding the flame 6-8" from the surface. Do not overdo the action with the torch as scorching of the epoxy can occur.