What causes floor blistering and bubbles?
Blistering undergo osmosis, which is defined as the movement of a solvent through a semi-permeable membrane from a less concentrated solution to a more concentrated one. Osmosis only occur in the presence of three factors:
When osmosis occur, moisture is moved up from the concrete surface, through the substrate and push underneath the cured resin which results in blistering. Blistering do not occur immediately, it takes a while for this pressure to build up.
Blistering can result due to the following:
- The coated surface is continually exposed to water or high humidity. The source of the moisture might originate from the concrete or water vapour coming up through the porous concrete from the ground or as part of the curing process.
- Air bubbles become trapped in the resin material during mixing and remain during cure
- Moisture vapour transmission
- Applying resin material onto a porous substrate
Bubbles, on the other hand, is not the result of water damage but environmental or substrate problems, particularly during the drying or curing process. Below are scenarios that can cause bubbles formation on resin flooring:
- Environmental factors, for instance, floor coating is being applied outside in hot weather, the top layers will dry faster than the bottom layers. Bubbling might occur as differences in temperature meet.
- Substrate is too porous for the chosen floor coating
- Temperature is outside the recommended range during application
- Thick floor coating layers may cause uneven curing
It is better to anticipate possible problems and go with the right installation before problems surface which will result in time consuming process and costly to repair. Below are some preventive measures to reduce the problem of blistering and bubbling in resin flooring:
Do moisture test on substrate
It is recommended to measure the moisture content of the substrate before any application, during curing and after it has dried (for new applications). The moisture content must be less than or equal to 4% by surface moisture content of the concrete substrate. A moisture meter can be used to conduct such testing. The test will determine the type of floor coatings suitable for the project and whether a moisture vapour barrier is required.
Select the correct floor coating material
Typically polyurethane solutions offer breathability on moist and damp substrate whereas epoxy solutions do not and will require damp proof membrane prior to installation. To find out more about the difference between epoxy and polyurethane coatings, read this post. A simpler way is to choose a water vapour permeable product or system. In this way, moisture can escape and will not be trapped underneath, thus reducing the chances of blistering.
It is important that the coating components are mixed thoroughly and evenly distributed during mixing and that it is evenly applied.
Experienced and skilled installation
Get a flooring specialist to inspect the facility beforehand to ascertain the environmental factors that may affect the new flooring. A highly skilled and trained applicator who knows what they are doing will ensure a smooth operation.