Summer Humidity Swings Increase Corrosion Risk for Metal Shipments
June 26, 2026
Summer has hit the Northern Hemisphere, bringing a rollercoaster of temperature and humidity swings to many areas. While individuals out in the sun try to avoid heat exhaustion by drinking plenty of fluids and staying cool with popsicles, manufacturers face a similar but slightly different challenge for metals protection: navigating the higher risk of corrosion from hot, humid air and temperature swings. A great solution to keep on hand for a quick boost of protection is Desicorr® VpCI® Pouches, dual moisture-absorbing, corrosion inhibiting materials.
Why Is Summer Considered Rust Season?
Summer is sometimes called “rust season” because higher temperatures and higher moisture content in the air accelerate corrosion rates. This gets tricky for manufacturers trying to keep freshly machined metal parts from corroding. A box of brake discs sitting in a temperature-controlled QC (quality control) office one moment may suddenly be moved to a hot, humid warehouse or truck where the cool metal is a magnet for moisture condensation from the muggy air. Similarly, multiday cross-country trucking will expose a shipment of machined parts or mechanical controls to extreme night and day temperature swings that further encourage condensation and the corrosion that can follow.
Why Can Moisture Removal Be Inadequate?
The traditional approach to moisture absorption is to add desiccant pouches to a package or enclosure. This can help remove one cause of corrosion, but it does not offer active protection against any moisture (not to mention other corrosive material) that reaches the metal surfaces before absorption begins or after the desiccant is spent.
Benefit of Two-in-One Package Protection
Desicorr® VpCI® Pouches go beyond moisture-absorbing action by combining desiccant and Vapor phase Corrosion Inhibitors in the same package. These protective vapors diffuse out of a breathable membrane and throughout the enclosure in which they are placed, forming a molecular layer on metal surfaces to inhibit corrosion reactions even in the presence of humidity or other corrosives. By combining moisture absorption and corrosion inhibition, Desicorr® VpCI® Pouches can enhance corrosion protection strength while still addressing other moisture-specific concerns for sensitive components.
How to Calculate the Right Amount of Desiccant / VpCI® for Your Package
Desicorr® VpCI® is typically dosed based on the size of the package or space in need of protection. The Desicorr® VpCI® 1/6 Unit and 1 Unit offer sufficient corrosion protection for enclosures of 1 and 5 ft³ (28 and 140 L) with a moisture absorption capacity of 1.32 and 9.9 g, respectively.* These smaller sizes are available in windowed versions to reveal when indicator spheres are spent. Larger packages with volumes of 20 or 40 ft³ (560 or 1,120 L) can use Desicorr® VpCI® 4 Unit or 8 Unit nonwindowed pouches, respectively, which offer moisture absorption capacities of 39.6 or 79.2 g. All versions now have stronger seal strength to avoid the accidental breakage and release of beads.
A Quick Fix for Summer Shipping Corrosion
With temperatures and humidity rising across the Northern Hemisphere, now is a great time to reevaluate shipping conditions and packaging strategies for “rust season.” Throwing more desiccant at the problem, hoping it will be enough to take care of moisture and corrosion, is no longer the go-to option thanks to the availability of dual desiccant/corrosion inhibiting materials that can be manually or automatically added to packages. Contact Cortec® for further advice on addressing heightened corrosion concerns during summer humidity and temperature swings: https://www.cortecvci.com/contact-us/
* Moisture Absorption Capacity (g) at 77 °F (25°C), 75% RH.
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