ZERUST® ICT® VCI Bags

VCI stands for Volatile or Vapor Corrosion Inhibitors. ZERUST® applies VCI technology to inhibit corrosion on metal surfaces. VCI film is packaging that generally consists of polyethylene film that has been impregnated with chemical formulations that are unique to each manufacturer. While the underlying formulations can vary significantly, the finished products function similarly in that they release very low concentrations (typically in parts per ten-thousandth) of invisible corrosion inhibiting vapors into the surrounding air. The vapor molecules subsequently condense onto exposed metal surfaces and form a molecular corrosion shield that can protect against rust and other forms of corrosion for many years. Typical service life is up to three (3) years and even longer in some cases. When the VCI packaging is later removed, all vapor corrosion inhibiting molecules rapidly evaporate. This leaves the metal parts clean and ready for immediate use.

ZERUST® VCI products prevent corrosion in several ways:

1. By acting as a protective barrier from external corrosive atmospheric elements such as abrasion, water, dirt, and acid gas pollutants.
2. By emitting Volatile Corrosion Inhibitors that passivate the electron flow between the anodic and cathodic areas on metal surfaces and interrupt the electrochemical corrosion process.
3. By adding water repulsion properties to the metal surface, which inhibit water from permeating the metal surface and providing the electrolyte for corrosion reactions.

The vapor corrosion inhibitor portion of ZERUST® VCI products is made of proprietary chemical formulations that are invisible, odorless, non-toxic, non-reactive, non-flammable, and non-allergenic. These chemical formulations release a corrosion inhibiting vapor that diffuses throughout an enclosure that either contains VCI formulations or is made from VCI materials and settles on exposed metal surfaces to form a microscopic corrosion inhibiting layer.

This protective layer will remain on the surface of the metal if there is no significant, continuous exchange of air within the enclosure. Ideally, there should be less than one air exchange per day (for example, when an electrical cabinet or package is opened briefly and occasionally). Once the metal part is removed from the enclosure, the corrosion inhibiting layer is no longer kept in place by equilibrium with the VCI source, and it dissipates from metal surfaces (typically within about an hour), leaving the metal part clean, dry, and corrosion-free.

The vapor diffusing properties of our corrosion inhibiting formulations offer an important advantage over conventional inhibitor coatings since the traces of these gas molecules penetrate hard-to-access crevices, gaps, and slots. They also cover the surfaces of complex-shaped articles that are difficult to coat. They are adsorbed onto the surface of the metal to form a corrosion inhibiting protective layer that is just a few molecules thick. ZERUST® VCI products may also include acid gas absorbing chemicals in the packaging material to act as a barrier and add another dimension to the protection of the metal content. These “scavenging” chemicals react and neutralize the polluted air that may diffuse through the ZERUST® VCI material. Also used are various combinations of physical barrier properties that optimize the corrosion prevention and physical protection needs of our customers. These may range from plain low-density polyethylene (LDPE) material to combinations of higher strength, higher tear resistance, higher resistance to sunlight or UV, static charge dissipation, and lower diffusion for moisture or acid gas molecules.

ZERUST® VCI products offer corrosion protection without having to be in direct contact with or coated onto the parts that are being protected. Metal parts merely need to be enclosed in or with a ZERUST® VCI product (where airflow is minimized) for protection to occur. With ZERUST® VCI packaging, it is no longer necessary to apply messy oils, greases, and other corrosion protection compounds and incur the cost of their removal.

Depending on the design of the corrosion prevention solution, some ZERUST® VCI packaging products may be produced from low and high-density polyethylene resins that are resistant to vapor penetration. Some atmospheric moisture will eventually find its way into a closed package. The presence of moisture in a package can be expected during shipments across areas of high humidity.

When moisture permeates through the ZERUST® VCI plastic packaging products (flexible and rigid), the moisture is affected by the vapor corrosion inhibitors that are present in the VCI product. As a result, the ZERUST® VCI products inhibit corrosion despite a low level of moisture passing through the plastic. Corrosion problems arise when moisture can enter a package unimpeded by the packaging products, such as through an incorrect closure or a significant hole in the package. For example, when there is a significant breach in the package, the corrosion inhibiting molecules can escape, breaking up the protective corrosion inhibiting molecular layer that had formed on the surface of the metal. Therefore, an unimpeded airflow into the package must be avoided.

ZERUST® VCI paper/plastic packaging does not affect the functionality of electronic circuitry, nor negatively react with non-metallic surfaces such as plastics, rubbers, or wood. However, since there are so many possible combinations of chemistries, materials, processes, and substrates, we always recommend contacting a ZERUST® account manager to validate the application. Other rust prevention methods such as oils, greases, and other liquid RPs (rust preventatives) pose a much higher likelihood of reacting with plastics, rubbers, and wood.

When a corroded item is packaged in ZERUST® VCI products, the corrosion process is slowed. However, our packaging products cannot remove corrosion that has already formed.

When wet parts are packaged in ZERUST® VCI products, a certain amount of corrosion can be anticipated to take place. The amount of corrosion will be a function of the time it takes for the active corrosion inhibiting molecules to saturate the package enclosure, the corrosion inhibiting effectiveness of the designed VCI system, the amount of moisture on the part, and the pH and contamination of the water itself.

Tests performed with electron spectroscopy for chemical analysis (ESCA) show that 2-4 hours after a steel panel is removed from a ZERUST® VCI package, all traces of the corrosion inhibiting molecular layer are gone from the surface of the part.

The period of time before one can expect corrosion to occur on a part depends on the cleanliness of the part and the environment around the part (relative humidity, presence of pollutants or wood, temperature, etc.)

The time required for active corrosion inhibiting molecules from a VCI product to saturate a package is a function of the volume and temperature of the package. Therefore, protection begins as soon as corrosion inhibiting molecules reach the metal surface, and maximum protection is achieved when the entire environment of the package is saturated with the corrosion inhibiting molecules.

Test data show that ZERUST® VCI products do not adversely affect electrical and electronic components. In fact, the corrosion inhibiting molecules help improve the reliability of electrical and electronic components by preventing corrosion that is too small to be seen by the naked eye. Therefore, it is safe to use ZERUST® VCI packaging products to prevent corrosion of any instruments, devices, and equipment that contain electric and electronic components.

Keep VCI products in original packaging until use. Store in a dry, covered warehouse between 0°F to 85°F (-18°C to 29°C) with a relative humidity of less than 60%. When not using ZERUST® VCI material for an extended period, enclose it in airtight plastic packaging to prevent atmospheric contamination and preserve the VCI. Reclose packaging at the end of shifts or during downtime.

VCI Bags, or Vapor Corrosion Inhibitor bags, are made with 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. This layer inhibits the corrosion process caused by oxygen, water, and contaminants. VCI bags are typically used when you want to protect metal parts from rust during storage or shipment but don’t want to paint or coat the parts in a rust preventative coating.

VCI bags, or vapor corrosion inhibitor bags, emit VCI molecules that settle on the metal surface and form an invisible layer protecting from rust and corrosion. VCI Bags protect against corrosion by interrupting the electrochemical corrosion process caused by moisture, oxygen, and contaminants in the atmosphere.

Most ZERUST®/EXCOR® VCI film products have a shelf life of up to three years when the product is stored in original airtight packaging, out of direct sunlight, and under shelter. Other products such as VCI Kraft paper, VCI emitters, liquids, and rust removers may have a shorter shelf life. Please refer to each product’s infosheet for the correct shelf life.

ZERUST®/EXCOR® VCI provides effective corrosion protection for clean metals for years^‡ when used correctly and utilized within three (3) years from receipt. ZERUST®/EXCOR® VCI products should be stored in original packaging away from direct sunlight in conditions below 85°F (30°C) and 50% RH until it is ready for use.

The component/part or volume needing protection must be completely enclosed by a ZERUST®/EXCOR® active material (VCI Poly/VCI Paper). If complete ZERUST®/EXCOR® packaging is being used, no additional VCI material is required. However, this also depends on the nature of the packed merchandise. If there are difficult-to-access areas, it is advisable to use additional ZERUST®/EXCOR® VCI Emitters and Diffusers to add additional protection.

ZERUST®/EXCOR® VCI film and bags can be reused if they are dry, clean, and undamaged. Small holes in the VCI film material can be sealed with adhesive tape. VCI bags that have large holes or tears or have begun to crack or lose strength due to excessive exposure to direct sunlight will not provide adequate corrosion protection and should not be reused.

The more tightly sealed the VCI packaging, the better the volatile corrosion protection. Seals may be closed with zip-ties, packaging tape, or staples. A good closure method is to fold over the film and either tape or staple the area shut. When stapling, seal over the holes made by the staples with tape. The best seal is always a heat seal, but it is not necessary. Also, it is unnecessary to extract air from the enclosure before sealing to prevent future airflow. Water must be prevented from penetrating the packaging. Be careful to fold over the film and close VCI gusset bags so water cannot easily pool and enter the enclosure.

Use a high-quality packaging tape that is designed to adhere to low-energy surfaces like polyethylene or, you can fold over and staple the area shut and then seal over the holes made by the staples with the recommended tape. If you have a large rip that you cannot close easily with tape or staples, you should replace the bag with a new one. The best seal is always a heat seal.

After removal of ZERUST®/EXCOR® packaging, the VCI substances present on the metal surface disperse within one to two hours.

Both VCI packaging products are useful, but one may be a better option depending on the application. VCI paper releases VCIs more rapidly than VCI film, but does not have as long of a service life. VCI film acts as a barrier to water vapor, whereas dry paper readily absorbs moisture. Other characteristics of the product needed could include formability, visibility of parts, and outer packaging used. The application should be oriented toward the goods to be protected and the details of the manufacturer’s packaging operations. A ZERUST®/EXCOR® representative can advise you on this.

A light oil coating on the metal part is fine to use with ZERUST®/EXCOR® VCI bags and film. A heavy oil coating may affect the performance of the VCI bag by keeping the vapor corrosion inhibiting molecules from reaching the metal surface. Please contact ZERUST®/EXCOR® to determine the suitability of the oil and application.

Ferrous: Iron, steel, and cast iron metals are protected using ZERUST®/EXCOR® Ferrous Packaging.
Non-Ferrous: Aluminum (and aluminum alloys containing copper and/or manganese), copper, brass, bronze, and fully galvanized steel are protected using ZERUST®/EXCOR® Non-Ferrous Packaging.
Multimetal: Products that contain combinations of the Ferrous and Non-Ferrous metals listed above can be protected by ZERUST®/EXCOR® Multimetal Packaging.
Silver: Is protected from tarnishing with ZERUST®/EXCOR® anti-tarnish packaging or film with acid-gas scavenger additives.

Yes. ZERUST®/EXCOR® VCI films made of polyethylene and polypropylene can be recycled at facilities for PE/PP processing or incinerated.

ZERUST®/EXCOR® VCI packaging products are produced using only virgin materials to ensure high quality and consistency for our customers. However, environmental consciousness is on the rise. As a result, companies are increasingly seeking innovative ways to reduce their carbon footprint and promote sustainability. Consequently, one such approach that’s gaining traction is post-consumer recycling. Here at ZERUST®, we’re at the forefront of implementing this technology across our VCI polymer film solutions. Furthermore, by incorporating post-consumer recycled materials into our VCI polymer packaging products, ZERUST® is reducing the demand for virgin plastics and promoting the circular economy. Moreover, by choosing ZERUST® products, businesses can protect their metal assets, reduce their environmental footprint, and join the global effort to build a more sustainable and responsible future!

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