VCI Corrosion Protection: Metal Part Shipment & Storage

Anti-corrosion papers, poly bags and sprays protect metals from corrosion (rust) during shipment and storage. Most of these are made with Volatile Corrosion Inhibitor (VCI) technology. What is VCI, and how does it work to prevent corrosion? You’ve come to the right place to find out.

What is a Volatile Corrosion Inhibitor (VCI)?

A Volatile Corrosion Inhibitor (VCI)—sometimes called a Vapor Corrosion Inhibitor—is a volatile chemical compound that decreases the corrosion rate of a metal or metal alloy. Volatile compounds are chemicals that vaporize in the air. A VCI compound can be infused into another material, such as paper or plastic, to give it protective properties. When a metal part is wrapped in VCI paper or enclosed in a VCI poly bag, the volatile compound diffuses into the air and condenses onto the metal, where it forms a thin layer of protective molecules. These molecules prevent water and oxygen from reaching the surface of the metal, inhibiting the corrosion process. VCI products include:

• VCI Paper
• VCI Poly Bags
• VCI Sprays

VCI Packaging Materials and Protective Sprays

VCI packaging materials and protective sprays play an important role in the packaging industry. Metal parts and machinery are some of the most valuable commodities shipped in the U.S. and globally. Unfortunately, many of these parts—especially components made of iron or mild steel—are highly prone to corrosion or rust. Corrosion damage in shipping costs is extremely costly for parts manufacturers and shippers. VCI packaging materials can help manufacturers and shippers avoid costly damage claims and ensure that parts arrive at their destination safely. VCI packaging is widely used in the automotive, aerospace and metal fabrication industries.

What is VCI paper used for?

VCI paper sheeting and VCI paper rolls are used as wrapping and product protection when shipping corrosion-prone metal parts and objects. Ready-to-use sheets are convenient for wrapping small parts, while rolls provide flexibility for larger parts of varying sizes. The VCI compound is impregnated in Kraft paper. It slowly diffuses out of the paper to form a protective barrier on the wrapped part. VCI paper can be used for shipping or storage of metal parts. VCI paper provides shock absorption and void fill properties in addition to corrosion protection. It is also very versatile for sharp, unwieldy or irregular parts that might puncture a poly bag, such as metal supports.

What are VCI poly bags used for?

VCI poly bags are a great option for shipping and storing metal parts and equipment. They come in a variety of sizes, from small 12x18” VCI poly bags for small parts to giant gusseted VCI bags to cover entire pallets or small-to-medium-sized equipment. Flat VCI poly bags are great for small flat parts like gears, nuts and bolts or flat sheets of metal. Gusseted VCI poly bags are perfect for irregularly shaped or dimensional parts and tools or larger pieces such as an engine block or mold. They can also be used as Gaylord liners inside a crate or carton. VCI poly bags provide superior protection from dirt, dust and moisture in addition to corrosion protection. Since they are transparent, it is easy to see what’s inside without unwrapping.

What is a VCI spray used for?

VCI sprays are sprayed directly on the product to form a corrosion-resistant barrier right on the metal. They provide effective corrosion resistance when applied evenly on the metal surface. The part can then be packaged as usual with typical packaging materials. Sprays may be the best choice for long-term storage of items such as engine blocks, tools and molds.

What are the advantages and disadvantages of VCI packaging materials?

When used correctly, VCI packaging materials provide effective, long-lasting corrosion protection. This prevents expensive damage to parts and equipment during storage or shipping.

The main drawback of VCI packaging is cost. VCI paper or poly bags are much more expensive than their non-VCI counterparts. There are also many more size and product variation options in non-VCI packaging. It is best to use VCI packaging only when it is really needed.

How long do VCI corrosion inhibitors last?

VCI materials can provide long-lasting protection against corrosion for metal parts. To maximize protection, store VCI materials away from heat and moisture and minimize exposure of the materials to air. Poly bags or paper should be wrapped or stored in a container or bag without excess air inside. When stored correctly, the shelf life for paper is about two years and the shelf life for poly bags may be up to three years. This is also about the length of time you can expect protection to last for a wrapped or bagged item.

The volatile compounds in VCI protectants will dissipate over time as they react with the atmosphere and the metal. For long-term storage, consider using a spray that can be refreshed periodically or replacing the packaging every couple of years. Do not otherwise open the packaging during storage; the molecular layer on the part will dissipate within hours once the part is unwrapped.

Another potential pitfall when using VCI packaging is the potential for user error. The product must be completely enclosed by the packaging material to prevent rusting. That means paper must be wrapped completely around the object, with minimal air left inside, and poly bags must be closed. For best results, completely enclose the object, avoid opening the packaging, and reduce exposure to high heat and humidity.

Also, remember that VCIs will not reverse corrosion already in process. If the part is actively rusting, it should be thoroughly cleaned to remove rust spots prior to storage. Make sure pieces are clean and dry before packaging.

How much do VCI packaging materials cost?

VCI packaging is significantly more expensive than non-VCI paper or poly bags—typically several times more expensive. When you consider the high cost of replacing corroded parts and equipment, however, VCI packaging is a very good value.

Pricing for VCI materials is highly volatile and dependent on raw material costs and supply lines. It may be cheaper to buy VCI packaging in bulk. However, because this product does have a shelf life, it is best not to buy more than you plan to use within a few months to a year.

How does VCI technology work?

VCI technology inhibits corrosion on metals and metal alloys by forming a thin protective layer on the metal. Corrosion is a chemical process in which materials (usually metals) interact with oxygen in the air or in water. The chemical reaction transforms a metal into a metal oxide, which we call rust. A VCI chemical compound is attracted to the metal. It forms an ion barrier that prevents water and oxygen from reaching the surface. It also displaces any water already condensed on the metal surface. By preventing oxygen and water molecules from interacting with the metal molecules on the surface of the object, VCIs can stop or slow the oxidation process.

What materials can be protected with VCI technology?

VCI technology is most often used with metals and metal alloys that are susceptible to corrosion when exposed to air or water. These include steel, iron and other iron-containing (ferrous) alloys. VCIs are most commonly used to protect metal parts and components made from iron and steel. Other metals—such as copper, chrome and aluminum—may also benefit from VCI protection to prevent the formation of undesirable surface characteristics. VCI is not typically used for plastics, glass and other non-corrosive materials. It should not be used when shipping items meant for human or animal consumption.

Can VCI packaging be used with electronics, rubber, wood, plastic and other non-metallic parts?

VCI paper and VCI poly bags are considered safe to use with electronics and with other materials such as rubber, plastic and wood. The VCI molecules do not react with most common non-metallic materials. However, chemical reactivity has not been tested with all possible materials. If you are not sure about the safety of VCI with your material, contact us or the manufacturer for support.

Is VCI safe?

VCI packaging materials are safe when used according to directions. VCI chemicals should not be inhaled or ingested. When using sprays, personal protective equipment (including masks, gloves and eyewear) may be recommended. Use an eyewash station if the spray gets in your eyes. Gloves are also recommended when handling VCI paper or VCI poly bags. VCI molecules inside protective packaging dissipate quickly, so inhalation and contact risks when using these materials are considered to be minimal. However, VCI materials should never be used to wrap foodstuffs, and workers should wash hands after handling VCI materials.

What is the difference between VCI and a desiccant for corrosion resistance?

Desiccants are a form of passive corrosion resistance. They absorb moisture from the air like a sponge. Reducing the humidity level inside the packaging will slow down corrosion. VCI technologies, in contrast, are a form of active corrosion protection. They react with the metal to create a protective molecular layer that seals the metal surface from exposure to oxygen and water.

What is the best option for corrosion-resistant packaging?

Benchmark offers high-quality VCI corrosion resistance packaging, including VCI paper and VCI poly bags. We work with our suppliers to provide you with the best quality product at the best possible price.

Not sure which type of corrosion protection is right for you? Talk to one of our Benchmark Product Experts. Call 844-423-6246 for support.