Bubbles and pinholes form when air or gas moves through wet epoxy and becomes trapped during cure. Small open craters are pinholes; raised defects are bubbles or blisters. Identify the cause before recoating.
Porous concrete contains air. As the slab warms, air can escape through wet epoxy and create defects. This is common when coating a warming slab or concrete in direct sunlight. Apply under stable or falling substrate temperatures and avoid rapid heating during cure.
Pores, cracks and voids release air. Mechanically prepare the floor, remove dust and use a compatible primer. Highly absorbent areas may need additional wet-on-wet primer. Do not rely on a thick finish coat to seal the slab.
High-speed mixing, whipping or repeatedly lifting the mixer can entrain air. Use a low-speed mixer with the correct blade, keep it submerged and mix for the specified time. Incorporate material from the sides and base without folding in excessive air.
Excessive thickness, vigorous rolling, overworking curing material or an unsuitable roller can trap air. Apply at the specified coverage and maintain a wet edge. For self-levelling epoxy, use a spiked roller only within the working period.
Moisture vapour, oil, silicone and contamination can produce craters, blistering or adhesion loss. Test concrete, remove contamination and use an appropriate epoxy vapour barrier where significant moisture transmission exists.
Allow the coating to cure, then sand or grind the area and remove dust. Fill remaining pores with compatible epoxy before recoating. Widespread defects may require removal to sound material, repriming and recoating. Correct the cause first.