Learn what causes your salt to clump up during humid weather. Discover how moisture absorption is the culprit and how to prevent it.
1 Answer
Salt clumps in humid weather because salt is hygroscopic, meaning it readily absorbs moisture from the air. This absorbed moisture creates a thin film of water on the salt crystals, which then dissolves some of the salt, and when the water evaporates, the salt recrystallizes, binding the crystals together.
Detailed Explanation:
The phenomenon of salt clumping, also known as caking, is primarily due to the hygroscopic nature of sodium chloride (NaCl), the chemical compound that makes up common table salt. Hygroscopic substances have a strong affinity for water molecules. When the humidity in the air is high, salt crystals attract and absorb water vapor from the atmosphere.
This absorbed moisture forms a thin layer of saturated salt solution on the surface of the individual salt crystals. The salt at the surface dissolves into this thin film of water. As the humidity fluctuates, or as the water evaporates, the dissolved salt recrystallizes. This recrystallization process creates solid bridges between adjacent salt crystals, effectively gluing them together and forming larger clumps.
The presence of impurities in the salt can also exacerbate clumping. Some salts contain trace amounts of magnesium chloride or calcium chloride, which are even more hygroscopic than sodium chloride. These impurities attract even more moisture, accelerating the clumping process.
Pro Tip:
To prevent salt from clumping, store it in an airtight container with a desiccant like rice or a silica gel packet. The desiccant will absorb excess moisture, keeping the salt dry and free-flowing.