Desiccants vs Volatile Corrosion Inhibitors (VCI)

Desiccants vs Volatile Corrosion Inhibitors (VCI)
Published On: August 5, 2021 Revised On: February 28, 2024

Safeguarding goods during storage and transit is crucial in the global supply chain. As products traverse various climates and conditions, they are exposed to risks like moisture and corrosion, which can compromise their quality. To counter these challenges, industries often turn to two primary protective packaging solutions: desiccants and Volatile Corrosion Inhibitors (VCIs).

Desiccants absorb ambient moisture, ensuring products remain dry and unaffected by humidity. On the other hand, VCIs release a protective layer of molecules that settle on metal surfaces, shielding them from the corroding effects of their environment. This article delves into the specifics of both methods, offering insights into their applications and effectiveness.

Understanding Desiccants

Desiccants are substances specifically designed to remove moisture from the environment in which they are placed. They achieve this through a process known as adsorption, where water molecules are bound to the surface of the desiccant material. The absorbers attract water molecules from their surroundings.

The process is not about absorption; a material takes in the moisture and becomes wet. Instead, desiccants work through adsorption, whereby the moisture adheres to the surface of the desiccant, keeping the surrounding environment dry. Desiccants play a pivotal role in many sectors, safeguarding products and assets from the detrimental effects of excess moisture. Their varied types cater to specific needs, ensuring every industry has a tailored solution to its moisture-related challenges.

Pharmaceuticals rely on them to maintain drug efficacy and shelf-life in humid conditions. In the electronics sector, they’re used to thwart moisture-induced malfunctions. Food businesses utilize these agents to fend off mould and spoilage. They’re also crucial in shipping, preventing moisture damage during lengthy transits. Notably, museums and storage facilities use them to preserve artefacts and historical documents, maintaining their integrity over time.

Desiccants vs Volatile Corrosion Inhibitors (VCI)

Types of Desiccants:

  • Silica Gel: An excellent drying agent that absorbs moisture and protects against contamination, spoilage, and mould growth. There are three distinct degrees of humidity detection and control: white, blue, and orange. It is an amorphous silicon dioxide with an uneven atom structure.
  • Calcium Oxide: Also known as quicklime or burnt lime, calcium oxide is a potent desiccant known for its high moisture-absorbing capacity. It undergoes a chemical reaction with water to produce calcium hydroxide.
  • Molecular Sieves: Made from synthetic zeolites, molecular sieves are porous materials with uniformly sized pores. Their specificity allows them to selectively adsorb gas or liquid molecules based on size, making them incredibly efficient at moisture removal.
  • Activated Clay: A natural, mineral-based substance, activated clay is often used in environments where relative humidity is moderate. It is known for its cost-effectiveness and environmentally friendly characteristics.
  • Activated Alumina: Made from aluminium oxide, activated alumina is porous and highly absorbent, making it particularly effective in removing water vapour from gases and liquids. It is often used in heavy industrial applications, including adsorbing catalysts and eliminating fluoride and pollutants.

Exploring Volatile Corrosion Inhibitors (VCI)

Volatile Corrosion Inhibitors (VCIs) release vapour into the environment to protect metals from corrosion. These vapours condense on the metal surfaces, forming a thin, protective film that prevents moisture and other corrosive agents from reacting with the metal.

Upon release, the VCI compounds vaporize and are drawn to metal surfaces. Here, they bond electrochemically to the metal, forming a molecular barrier. Although invisible and mere molecules thick, this protective layer effectively isolates the metal from corrosive agents, such as oxygen and moisture. VCIs can be used in various industries seeking to prolong life and maintain the quality of metal components.

The automotive sector uses them to prevent the rusting of parts during storage and transport. Electronics industries apply VCIs to protect components from corrosion, ensuring device longevity and performance. Additionally, machinery and equipment manufacturers utilize VCIs, especially during export or long-term storage, to prevent damage that could compromise function. Their application also extends to the military for preserving weaponry and aerospace for protecting aircraft parts.

Types of Volatile Corrosion Inhibitors:

VCI Paper: Often used for wrapping or interleaving between metal parts, these papers are infused with VCIs. They release inhibitors that condense on the metal surfaces, offering a barrier against corrosive elements. They come in different sizes, weights, and inhibitor types and are ordered in rolls, pre-cut, and with custom printing. They can also be reinforced with a poly layer or scrim-like threads for additional protective properties. It is also sometimes referred to as a rust inhibitor paper.

VCI Film:  Typically made from polyethene or other polymers, these films are embedded with VCI compounds. When wrapped around metal objects, they emit protective vapours that envelop the metal, providing comprehensive protection. When the packaging is removed, the VCI molecules vaporise without requiring cleaning.

VCI Emitters: Also known as VCI diffusers, they provide targeted corrosion protection in hard-to-reach enclosed spaces. These devices or containers release VCIs in closed environments, like cabinets or boxes. Emitters are especially effective for protecting intricate or hard-to-reach metal parts within larger systems or assemblies.

VCI Liquids: Once the liquid has been adsorbed on the metal’s surface, it provides an effective hydrophobic barrier that prevents moisture from getting through to the metal surface. Consequently, this prevents the formation of corrosion. There is a wide range of rust inhibitor coatings ranging from oil-based, solvent-based, water-based, and grease-based to oil additives to protect parts between production processes and storage.

VCI Bags: A poly packaging film converted to a bag manufactured with added VCI chemistry. VCI molecules protect metals from corrosion by forming a thin, invisible layer on the surface that inhibits the corrosion caused by oxygen, water, and contaminants. The bags can be supplied in different sizes, weights, seals, and inhibitor types.

VCI Powder: Designed to protect metal surfaces in large voids from corrosion, it offers VCI protection combined with a new self-fogging Flash Corrosion Inhibitor (FCI) technology specialising in protecting metals in enclosed spaces. This combination diffuses rapidly to protect against flash rust and provides long-term corrosion protection with its progressive vapour-transported corrosion inhibitor action. The powder is fully water-soluble and is effective in wet lay-up applications.

Comparing Desiccants and VCIs

Regarding safeguarding goods, both desiccants and VCIs offer compelling benefits. The decision between the two often rests on the application’s specific requirements, the nature of the goods, and overarching logistical and environmental factors.

Protection Mechanism: Desiccants primarily function through moisture absorption. By actively drawing in ambient moisture and trapping it within their matrix, they create a substantially drier environment for products. This method ensures that goods sensitive to moisture, such as electronics or pharmaceuticals, remain in optimal condition.

On the other hand, VCIs offer a distinct mode of protection through molecular layering. They emit specialized compounds that vaporize and subsequently condense on metal surfaces. This action protects against potentially corrosive agents, ensuring metals remain untarnished and functional.

Efficiency: Desiccants excel in environments with fluctuating humidity levels. They are particularly adept at maintaining dry conditions and safeguarding susceptible products. However, one limitation to note is their finite absorption capacity. Once saturated, their efficacy diminishes, necessitating periodic replacement or regeneration.

VCIs, in contrast, cater specifically to metals, offering them consistent protection. Their efficiency is remarkable, even in challenging environments, and remains in effect as long as the VCI compounds are active and the protective barrier stays intact.

Cost Implications: Desiccants generally present a more favourable upfront cost, making them an attractive option for many industries. However, their ongoing effectiveness can sometimes entail additional long-term costs, especially if regular maintenance or replacement is needed.

VCIs might involve a higher initial investment, particularly for specialized applications. But an advantage they bring is longevity. With their durable protection mechanism, the subsequent costs often plateau, reducing the need for frequent replacements or maintenance.

Ease of Application: Incorporating desiccants into packaging processes is usually straightforward. They commonly come in user-friendly formats like sachets or packets, ready to be placed within product containers. V

CIs, although equally beneficial, may require a tad more attention during application. While VCI films and papers seamlessly integrate into packaging, achieving optimal protection might sometimes demand precision in placement or adherence to specific conditions. VCI emitters, however, simplify the process, especially when placed within enclosed spaces.

Environmental Considerations: Desiccants present a mixed bag for environmental considerations. Some variants, like silica gel, are inherently non-toxic and eco-friendly. Others might need more cautious disposal to mitigate environmental impacts.

VCIs, in recent times, have seen significant advancements in their formulation. Many contemporary VCIs are crafted to be environmentally safe. Nevertheless, it remains imperative for users to ensure that their chosen VCI aligns with prevailing environmental regulations, especially concerning disposal.

A Comparative Summary

Protection MechanismAbsorb ambient moisture, creating a drier environment.Emit compounds that form a protective barrier on metal surfaces.
EfficiencyExcel in fluctuating humidity; limited by saturation point.Specifically cater to metals; remain effective as long as compounds are active.
Cost ImplicationsFavorable upfront cost; potential long-term costs due to replacement or maintenance.Higher initial investment; reduced long-term costs due to durability.
Ease of ApplicationStraightforward, usually in sachet or packet forms.Require attention for optimal protection; emitters simplify the process in closed spaces.
Environmental ImpactVaries; some are eco-friendly, while others need cautious disposal.Many modern VCIs are environmentally safe; always check alignment with regulations.

Combining Desiccants and VCIs

While desiccants and VCIs each offer unique protection mechanisms for goods, there are situations where utilizing both concurrently can amplify preservation efforts. By addressing moisture-related and corrosion challenges, they can holistically safeguard goods. As with any preservation method, attentiveness to best practices ensures optimal outcomes.

In environments characterized by fluctuating humidity levels or those laden with airborne corrosive agents, employing a dual strategy becomes more than just prudent—it becomes essential. Goods stored for long durations, especially metals, benefit immensely from the simultaneous moisture absorption of desiccants and the corrosion prevention offered by VCIs.

Additionally, when products traverse diverse climatic zones, the combination of desiccants and VCIs ensures they remain shielded from their varied external challenges. Another significant scenario is the storage or transit of sensitive equipment, especially those amalgamating electronic components susceptible to moisture, with metal parts prone to corrosion. Here, the complementary effects of desiccants and VCIs prove invaluable.

Benefits of a Dual-Protection Approach:

The coupling of desiccants with VCIs brings forth a plethora of benefits. Foremost among these is the enhanced durability of goods. By concurrently addressing moisture and corrosion, the chances of goods deteriorating or needing frequent maintenance diminish considerably.

Furthermore, this approach is cost-efficient in the long run. Despite the initial investment in both protection techniques, the potential reduction in spoilage or damage can yield significant long-term savings. Beyond these tangible benefits lies the intangible yet invaluable peace of mind for stakeholders. With the confidence that their products are shielded from a broad spectrum of environmental threats, they can focus on other core aspects of their operations.

Precautions and Best Practices:

  1. Avoid Overloading: While using both methods can be beneficial, it’s crucial not to overwhelm the packaging or storage space. Ensure there’s a balance to maintain product integrity.
  2. Monitor Saturation Levels: Especially for desiccants, it’s vital to track their saturation levels and replace or regenerate them as needed.
  3. Ensure Proper Placement: Both desiccants and VCIs should be placed to allow optimal circulation, ensuring their protective effects reach all parts of the stored goods.
  4. Regularly Inspect for Damage: Periodic checks should ensure neither the VCIs nor the desiccants have been compromised and continue to offer effective protection.


The protective measures heavily influence the integrity of goods, whether in storage or transit. The choice between desiccants and VCIs depends on the specific needs of the items. Making the right selection ensures optimal preservation and reduces potential damages.

Humi Pak offers an extensive array of desiccants and VCI packaging options. Manufacturing ISO 9001 and 14001 certified desiccant bags in Malaysia, we uphold rigorous quality standards. For tailored solutions and insights, feel free to contact our packaging engineers.