How to Solve Bubbling Issues When Applying Wall Putty/Gypsum
On construction sites, there are two common base layers: brick walls and concrete walls.
Bubbling typically occurs on concrete walls, primarily due to numerous through-pores present in the concrete surface. Therefore, to resolve bubbling when applying wall putty/gypsum, we must seal these through-pores.
1. Sealing Substrate Pores
The most common method is applying a primer or wall sealer to seal the pores in the substrate. This is also the most suitable, safest, and most effective approach.
Applying an emulsion-based primer can be done by roller or machine spraying. When machine spraying, avoid setting the air pressure too high to prevent liquid splatter, which could compromise the sealing effect.
2. Water Application
Some sites may use water application to seal pores, preventing bubbles during wall putty application. However, if neutral wall putty or gypsum mortar is used—which are not water-resistant—moisture migration later on can cause these materials to hollow out and detach.
3.Improving Through Application Techniques
When applying the first coat, apply it thinly to allow trapped air to escape. Then, use application techniques to eliminate any bubbles before applying the second coat.
4. Improving Through Mortar Formulation
(1) Use low-viscosity cellulose ether. Lower viscosity results in less dense mortar, allowing air bubbles to escape.
(2) Increase coarse aggregate content whenever possible. This enhances the mortar’s permeability, allowing bubbles from the substrate to escape and reducing the likelihood of surface bubbling.
Note: Adding defoamers is not recommended here. Defoamers typically eliminate bubbles generated within the mortar system and are ineffective against bubbles rising through wall pores, only increasing costs.
