For nearly 5 decades now, manufacturers and OEMs across the globe have been incorporating ZERUST® Vapor Corrosion Inhibitor (VCI) products into their packaging applications to prevent rust and corrosion during shipping and storage of their metal goods. However, despite years of experience, not everyone fully understands how VCI works and how to use it correctly to achieve the best performance. If you follow these guidelines, you will undoubtedly successfully prevent rust and corrosion when using ZERUST® VCI products.
VCI comes in various formats, from VCI poly bags and sheeting, VCI kraft paper, diffusers and emitters, and even powders and liquids. Regardless of which type of VCI you use, they all offer the benefit of releasing a vapor that contains the corrosion inhibitors that will protect your metals. Knowing this is critical when selecting the type of VCI product for your application, as the VCI vapors must be contained inside the environment where your metal is being stored or packaged. Bags must be properly sealed, boxes fully closed, and metal parts on pallets fully encapsulated to keep the VCI from escaping into the atmosphere. VCI bags, or plain poly bags containing other forms of VCI products, should be heat sealed, cable-tied, or folded and tape shut.
VCI works best to prevent rust and corrosion on metal that is clean and free of any contamination. In the metalworking industry, we often see manufacturers unknowingly package metal parts that contain chlorides, bacteria, or other known corrosion-causing ions left on their surface. This can be due to several reasons, such as fingerprint contamination, dirty workspaces, or, more commonly, poor metalworking fluid maintenance. In addition to having clean parts, VCI is optimized when the parts are fully dry before packaging. Even though most VCI chemistries, such as ZERUST’s, are water-soluble, VCI needs time to set up and form a protective layer on the metal surface before any moisture, such as condensation, is present. If metal parts are packaged wet or damp, the corrosion cycle can start before the VCI has adequate time to diffuse out and do its job.
Another thing to consider when using VCI is ensuring that the metal parts are at ambient room temperature before closing the packaging. If metal parts are packaged and sealed warmer than room temperature, they risk causing a greenhouse-like effect which can lead to immediate moisture due to condensation. The same can be true when unpacking metal parts packaged in VCI. An example is parts shipped in a warm warehouse during the cold winter months. To avoid possible flash corrosion occurrences, you would want the incoming parts to warm up to the ambient room temperature before opening.
Since VCI products are typically used in packaging applications, you must also consider what other packaging materials might be needed and the configuration of all packaging materials. You want to ensure that your metal parts are never in direct contact with any cardboard, non-VCI paper, or wood, as they can be sources of unwanted moisture and acid. Also, if dividers or interleave sheets are needed, ensure they are not blocking the path of the VCI source to the metal. In layered or large quantity packaging configurations, ensure there are additional VCI materials to protect each layer of metal parts inside a container.
ZERUST® VCI poly products can be recycled or disposed of similarly to any other similar LDPE products you handle. Our Kraft VCI Paper is fully recyclable, repulpable, and made from responsibly managed forestry products. ZERUST® is a registered trademark of Northern Technologies International Corporation “NTIC” and is the inventor of VCI film and bags. NTIC’s ZERUST® division is a full-on corrosion solutions provider offering VCI, rust preventative coatings, rust removers, wash chemicals, and technical services. You can click here for a quick “How to use ZERUST® VCI” reference guide.
For more information, call (763) 225-6600.