The POP should be stored in a moisture-proof containeras it absorbs water from moisture and turn into hard substance (Gypsum). CaSO4.1/2 H2O + 3/2 H2O -----> CaSO4.1/2 H2O

Introduction:
Plaster of Paris, also known as calcium sulfate hemihydrate, is a versatile material commonly used for making casts, molds, and sculptures. It is made by heating gypsum, a naturally occurring mineral, to remove the water content. Plaster of Paris has the property of setting quickly when mixed with water, making it a popular choice for various applications. However, due to its chemical composition and reaction with moisture, it is essential to store plaster of Paris in moisture-proof containers.

Reasons for storing plaster of Paris in moisture-proof containers:

1. Moisture absorption:
Plaster of Paris has a high affinity for moisture and readily absorbs water from the environment. This moisture absorption can lead to a change in its chemical structure, resulting in a loss of its desired properties. When exposed to moisture, the gypsum in plaster of Paris can rehydrate and turn into gypsum dihydrate, which is a weaker and less stable form. This can compromise the strength and durability of the plaster.

2. Setting time and quality:
Moisture can significantly impact the setting time and quality of plaster of Paris. If the plaster absorbs moisture from the air, it can start to set prematurely, making it difficult to work with and potentially resulting in a poor finish. Moisture can also introduce impurities into the plaster, affecting its setting properties and overall strength. By storing plaster of Paris in moisture-proof containers, we can ensure that it remains dry and maintains its desired setting time and quality.

3. Mold growth and degradation:
Moisture can create a favorable environment for mold and bacteria growth. Plaster of Paris stored in a moist environment can become a breeding ground for these microorganisms, leading to discoloration, foul odor, and degradation of the material. These effects not only compromise the aesthetic appeal of the plaster but also pose health risks for individuals handling or using it. Storing plaster of Paris in moisture-proof containers prevents moisture accumulation and minimizes the risk of mold growth and material degradation.

4. Longevity:
Proper storage conditions play a vital role in extending the shelf life and longevity of plaster of Paris. Moisture can accelerate the aging process of plaster, causing it to deteriorate and lose its usability over time. By storing plaster of Paris in moisture-proof containers, we can protect it from moisture-related damage and ensure its long-term usability.

Conclusion:
Storing plaster of Paris in moisture-proof containers is crucial to maintain its integrity, setting properties, and longevity. By preventing moisture absorption, we can preserve the strength, quality, and usability of the plaster, ensuring optimal results for various applications. It is essential to prioritize proper storage practices to maximize the performance and longevity of plaster of Paris.