Desiccant suppliers will tell you that the ability to absorb moisture is the most important factor to consider when choosing a desiccant. Obviously, the desiccant should absorb more moisture. What they don't mention is that the unique properties and applications of the desiccant must be considered when making a decision.
Let's see how this works with the examples of Topcod's calcium chloride desiccantand desiccant bentonite. Calcium chloride can absorb 300% more water than clay, while clay can only absorb 30-40% of water. Surely, the ability to absorb 10 times more water makes calcium chloride a far superior desiccant? This is not necessarily true.
Applications: Inside the package vs. shipping containers
Knowing where to use desiccant is critical. Calcium chloride requires high humidity to work. The package does not provide this. Calcium chloride does not absorb well when the humidity inside the package is not high or constant. It does not absorb much moisture and does so very slowly. Clay desiccant thrives under these conditions. It is more effective than calcium chloride and can reduce humidity faster.
Shipping containers are places where humidity is high and constant. Calcium chloride is most effective under these conditions. It removes moisture from the container and prevents rain. Therefore, it is an excellent ingredient for container desiccant. We use high quality calcium chloride in container desiccant.
Desiccant performance.
Consider what will happen if the desiccant absorbs water. Calcium chloride may turn into highly corrosive liquid jelly and may leak. Clay desiccants stay dry even when filled with water vapor. Another reason to avoid calcium chloride in packaging is that if the product leaks, it can cause irreparable damage to the product. We do not recommend using it on metals or electronics because calcium chloride can be corrosive.
