In this article, we explore the key differences between Calcium Chloride vs Silica Gel-based desiccants and their moisture-absorbing capabilities. Not everyone in the logistics sector is aware of the risks associated with sea transport. Annually, $500 billion worth of goods is lost due to container damage, with at least 10% of this loss attributed to moisture. Many companies are already taking action to combat moisture issues. They wrap products in special foil or use desiccants that absorb moisture to prevent it from affecting the products. Desiccants come in various forms and sizes, and they can be made from different materials.
Absorption Process of Calcium Chloride vs Silica Gel
Calcium chloride is highly hygroscopic and has the unique property of liquefying as it absorbs moisture. It can attract several times its own weight in water, causing it to dissolve into a gel-like substance. This process makes it effective in environments with high humidity, where rapid moisture absorption is needed.
Silica gel, in contrast, consists of a porous structure that traps moisture without breaking down. It can hold up to 40% of its weight in water while remaining dry to the touch, even when fully saturated. The actual absorption capacity varies based on temperature and humidity, but it remains a reliable option for controlled moisture management.
Comparing the Data
The tables and graphs below compare the two desiccants. These figures are relevant to the effectiveness of moisture protection during container shipments.
Comparison Table
| Calcium Chloride | Silica Gel | |
|---|---|---|
| Absorption Capacity Desiccant materials absorb greater amount of moisture when the relative humidity of the surrounding air is higher. | 150% At a relative humidity (RH) of 50%, moisture absorption reaches 150% of its weight in water. This absorption increases exponentially as RH rises, reaching 600% at 85% RH. | 25% At low RH, absorption is limited, with only 25% of its weight trapped at 50% humidity. Unlike the exponential absorption curve of other desiccants, its absorption increases in a more linear fashion, reaching only 36% at 85% RH. |
| Safe Against Exhaustion Some absorbers can exhaust themselves before the voyage has completed, due to temporary humidity spikes. | Yes The material is self-limiting, allowing it to provide long-lasting protection even during short periods of high RH. Spikes in humidity are dampened without causing the desiccant to become saturated. | No Water is absorbed into microscopic pores, and if a short spike in humidity occurs early in the voyage, all pores can become fully saturated, leaving the cargo unprotected. |
| Safe Against Re-Evaporation If absorbed moisture is re-released when humidity drops a “pumping” effect can be created, intensifying damage. | Yes Absortech products capture used calcium chloride and absorbed water into a chamber that prevents moisture from leaking into the cargo space or re-evaporating back into the air. | No Silica gel’s moisture absorption pores breathe water back into the air just as easily as they take it in, depending on shifts in temperature and relative humidity. |
| Environmentally Safe Many absorption materials contain moisture indicator additives that are classifies as toxic. | Yes Absortech products contain only calcium chloride, a naturally occurring compound abundant in seawater. Non-toxic, it can be disposed with regular wastewater. | No Many silica gels contain cobalt compounds, that are considered carcinogenic and require special disposal using hazardous waste procedures. |
Conclusion
From the comparison table, it’s clear that desiccants based on calcium chloride have a higher absorption capacity, which increases as the relative humidity rises. Unlike silica gel, which has a limited maximum absorption, the former can continue to protect the freight throughout the entire journey. Additionally, it captures absorbed water in a chamber that prevents moisture from leaking into the cargo space or re-evaporating back into the air. Calcium chloride is also environmentally safe, as it contains a naturally occurring compound abundant in seawater and can be disposed of through regular wastewater. In contrast, silica gel contains compounds that require special disposal using hazardous waste procedures.
We strongly recommend desiccants that utilise calcium chloride, which are featured in Absortech products. We would like to offer advice on moisture-related issues during container transport and how Absortech desiccants can help prevent damage to goods. Please get in touch for more information on how to protect your shipment from moisture problems.
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