When Labs Need to Lock In Dry Conditions, They Keep Choosing This Chemistry

Desiccant packets are a common sight in equipment and packaging, quietly protecting against ambient moisture during shipping and storage. But in a lab, the standards are higher. Water content must stay below strict thresholds—often in the single-digit ppm range—and remain stable over time.

That’s where desiccants diverge. Silica gel captures moisture in surface pores through physical adsorption. Calcium sulfate, by contrast, binds it through a chemical reaction that forms a new solid phase. This article explores how that difference shapes lab use, and why one drying agent continues to serve applications from passive containment to advanced sensing.

Where Drying Performance Starts to Matter

An independent research firm recently compared silica gel and Drierite®-brand calcium sulfate under controlled conditions using chilled mirror hygrometry¹. Both materials were exposed to fixed air volumes, regulated flow, and a stepped temperature profile ranging from 20°C to 50°C. Humidity was gradually lowered from ambient levels to below 10 percent.

Silica gel absorbed water quickly at higher humidity, particularly above 30 percent. But its uptake rate dropped sharply below 15 percent. At under 10 percent—where most lab systems operate—it slowed to a near standstill.

Calcium sulfate followed a different pattern. It maintained a steady rate as humidity fell and kept binding water into the single-digit range. Final humidity levels were lower and more consistent than those achieved with silica gel.

How Calcium Sulfate Dries—and Dries Again

Drierite desiccants are produced by heating naturally occurring gypsum to remove the bound water locked within its crystal structure. The process includes precise dehydration and particle size selection. The resulting solid has 38 percent pore space and high chemical potential—a strong drive to rehydrate. When water hits the surface, the material reacts to form a new solid, trapping each molecule within the growing structure.

That phase builds outward from the point of contact. As more water arrives, the reaction progresses inward in a slow, even front. The solid holds its shape and volume as density increases, which helps preserve drying strength over time.

In the late 1920s, calcium sulfate’s stability drew the attention of W. A. Hammond, a PhD candidate in chemistry at Ohio State University. He tested it in sealed systems and found that heating fully restored its drying power. The material remained solid, structurally intact, and ready for reuse.

Hammond also looked for techniques to make the desiccant’s saturation point easier to detect. He added a cobalt-based formulation that shifted from blue to pink as the material absorbed moisture, creating a visible signal when the capacity was reached. In 1934, he founded the W. A. Hammond Drierite Company to produce the material commercially.

From Trace Moisture to Mars-Like Extremes

Labs initially turned to Drierite because it combined chemical resilience with dependable moisture removal. It stayed solid in use, resisted reaction with solvents, and held its form under vacuum. After reactivation, it performed just as effectively. That reliability made it a practical choice in desiccators, drying tubes, and gas lines.

Decades later, those familiar blue granules remain key to modern research. In glycan and oligonucleotide synthesis, even trace amounts of water can alter outcomes or reduce yield. As part of a metal-free glycosylation strategy², researchers added Drierite directly to the reaction solvent to protect catalyst activity and maintain selectivity. Keeping moisture out of the system improved efficiency and reduced downstream cleanup.

Water control is just as critical in biosensing systems. In one nanosensor study³, researchers used dry storage to preserve particle stability before testing. In another report focused on metabolic rate in dogs⁴, Drierite desiccants removed water vapor from breath samples before gas analysis, ensuring consistent readings throughout multi-hour trials.

Researchers have also used Drierite to simulate extreme environments in the lab. In one Mars-analog study⁵, low-humidity chambers were used to test how desiccation and freezing affect microbial radiation resistance. Another investigation⁶ simulated drought-like conditions for invasive ants, revealing how body size influences survival. In both cases, passive moisture removal enabled the arid, controlled setups needed for reproducible data.

Extend Drying Beyond the Desiccator

         

Labs rely on tools that carry moisture control into every part of the workflow. Mini-dehumidifiers, designed for enclosed setups such as reagent safes and balance chambers, maintain low humidity without powered systems. For sealed glassware, Drierite Dry-Tops replace standard stoppers with chemically resistant chambers filled with desiccant. In gas chromatography, where even trace moisture can interfere with performance, Drierite gas purifiers clear the flow path to protect columns and detectors.

Outside the lab, Drierite desiccant bags mirror the format of standard silica gel—but with a formula built for deeper drying and stable performance.

On the plant floor, managing humidity often begins at the tank. Specialized Vent driers protect storage vessels and totes from water vapor drawn in during daily pressure and temperature shifts. Each unit is packed with Du-Cal Drierite, a formulation that combines calcium sulfate with a small amount of calcium chloride to enhance water uptake without compromising its structure. 

Conclusion

Moisture control may seem like a background task, but it influences lab performance at every level. Reliable drying extends equipment life, simplifies setups, and enables passive systems where active ones fall short. Drierite delivers stable, reliable drying without the need for complex infrastructure.

Discover drying tools that keep pace with innovation. Full product specifications and technical resources are available at drierite.com.

References

1. 1. https://www.labcompare.com/10-Featured-Articles/578841-Harnessing-Humidity-with-Chilled-Mirror-Hygrometry/
2. 2. Organic Letters, 24(49), 9028–9032 (2022) https://doi.org/10.1021/acs.orglett.2c03661
3. 3. Science Advances, 10(1), eadj9591 (2024) https://doi.org/10.1126/sciadv.adj9591
4. 4. Science Advances, 10(10), eadj3823 (2024) https://doi.org/10.1126/sciadv.adj3823
5. 5. Astrobiology, 22(11), 1337–1350 (2022) https://doi.org/10.1089/ast.2022.0065
6. 6. Journal of Experimental Biology, 226(16), jeb245578 (2023) https://doi.org/10.1242/jeb.245578
7.