What Does Effervescence Mean?
Effervescence refers to an effect in a film caused by rapid solvent release. It is the escape of gas from an aqueous solution. Blister-like surface defects will appear due to the entrapment of gases on the surface of the paint film. If these gases or bubbles are not fully removed, pinholes or craters will appear during the application of the next coat. So, solvent blisters and boils must be properly controlled to avoid pinholes and the loss of gloss.
Corrosionpedia Explains Effervescence
Effervescence is the escape of gas from an aqueous solution, which causes foaming or fizzing. Effervescence is seen when solvent boiling occurs during the evaporation of the surface coating and the formation of a coating film on the substrate.
Effervescence is also seen when opening a soft drink bottle. The visible bubbles released from the carbonated water are produced in the solution containing dissolved carbon dioxide gas (CO2). The chemical reaction that occurs in the soda water produces a gaseous product, carbon dioxide. Here, carbonic acid produces water and carbon dioxide. The reaction is:
H2CO3 ---> H2O + CO2
Effervescence produces pinhole marks on the coating film through solvent boiling or aeration of the old paint finish. It also causes a cratered appearance by reducing gloss. Sometimes the air or gas trapped in the pinholes will affect the top coat by rising to the surface. Pinhole marks can be prevented either by sanding out the holes/craters or by filling the holes.
The effect of solvent boiling on surfaces is minimized by sanding the paint coat's substrates and refinishing the coat with the proper selection of primers and top coats.