Answer :
Final answer:
A common problem with plaster applied over gypsum lath is the hardening of plaster containing slaked lime due to carbonation. Another issue is the potential for sulfur dioxide in flue gas to damage and discolor the plaster surface.
Explanation:
A common problem with plaster applied over gypsum lath is the hardening of plaster containing slaked lime (Ca(OH)2) due to the reaction with carbon dioxide (CO2). When plaster containing slaked lime comes into contact with CO2 in the air, it undergoes a chemical reaction which causes it to harden.
This hardening process is known as carbonation, and it can lead to the formation of cracks or a weakened bond between the plaster and the underlying gypsum lath.
Another issue with plaster applied over gypsum lath is the potential for the presence of sulfur dioxide (SO2) in the flue gas of power plants. Plaster, being a porous material, can absorb SO2 from the air, which can then react with moisture and form sulfuric acid. This can cause damage and discoloration to the plaster surface over time.
