Bubbles/Outgassing Over Porous Substrates:
The main cause of bubbles is outgassing which can be caused by a couple of different things, one of which is the porosity of the substrate that you are coating. Large holes, or cavities, that trap air and create pinholes in the epoxy as it's setting up. Another main culprit of outgassing is warmer temperatures or temperatures that are rising as the installation is taking place. When going over porous substrates such as concrete, wood, or raw stones, they outgas throughout the day and night, releasing and taking in air. Much like a sponge in water; as the liquid is being absorbed it releases air. When there is an excess amount of outgassing and the epoxy has started to cure, it will be too thick to let the air escape, trapping it in the coating and creating a bubble. Sometimes these bubbles do pop but the crater remains since the epoxy is no longer able to self-level back into itself.
What Are Pinholes:
Pinholes are noticeable after the epoxy has been applied. Large holes, or cavities, that trap air and create pinholes in the epoxy as it's setting up. These are usually not noticeable until you have prepped the surface/substrate, removing the top layer which will expose any air pockets/voids just underneath it. Following the coating application, they can usually be identified by looking for a small black dot/hole in the bottom of the bubble crater(s), and usually, these bubbles/craters will be the larger ones. If you can identify these specific ones we would recommend filling them manually per our “Imperfections Fix Guide”.