Abstract
The Plaster can expect the sterilization because slaked lime which is the main ingredients is tinged with alkalinity. However, slaked lime(calcium hydroxide) reacts with the carbon dioxide in the air, with progress of time, it will change to calcium carbonate (neutralization) and the effect will fade.It is expected that neutralization has a relation to the carbon dioxide levels and humidity in the air since calcium hydroxide reacts with the carbon dioxide in the air, turns into calcium carbonate and generates water. In this research, the action of neutralization was pursued in the long run, and it has grasped what kind of action is shown.And, change was given to humidity and the carbon dioxide levels in the air, the conditions of dryness were set as them, and it was verified what kind of influence humidity and carbon dioxide levels would bring the action of neutralization.
