Can you use silica gel together with VCI?

The short answer is yes. VCI and Silica gel function in different ways to reduce the risk of corrosion. VCI emits corrosion-inhibiting molecules designed to protect the surface of the metal.

Principles of operation

Silica gel is designed to absorb moisture from the atmosphere. As a rule of thumb, it is sufficient to keep relative humidity (RH) below 50%, although pharmaceuticals and certain compounds require RH below 10%. VCI and silica gel do not interfere with each other's respective functions, which means that VCI will not reduce a silica gel's ability to absorb moisture. The silica gel will not stop VCI from emitting its molecules. This is in itself a minor paradox, given that VCI uses water molecules to hydrolyze itself on the surface. This forms what is in many ways an electrolyte, as we know it from batteries. The difference is that an electrolyte with VCI will not conduct electricity between the anode and cathode, and thus corrosion ceases.

In other words, moisture is not a danger to VCI-protected components. But everything in moderation. After all, there is a limited amount of VCI molecules present. VCI can be washed away if there are large amounts of free water. Therefore, it may be appropriate to combine silica gel and VCI.

VCI and silica combo

It is important to give the VCI packaging an optimal starting point. We have described this in a separate blog post coming next week about how to pack with VCI plastic. In cases where it has been difficult to ensure dry goods when packing, we have let the silica gel do the work first by removing excess moisture, since, for example, silica gel does a very quick job to begin with. Later, the ability to absorb new moisture levels out a bit, but that does not matter. Once the silica gel has removed moisture, the VCI has time to build itself up slowly but surely on dry and clean surfaces.

Another effective proven packaging design using VCI and desiccants for overseas shipments is to apply 2 layers of plastic, with desiccants placed between the two layers. The inner layer, closest to the parts, must be VCI, and the outer bag can be pure poly/plastic, preferably shrink wrap that has UV resistance.

The silica gel between the two liner bags will reduce the humidity inside without compromising the protection of the metal.

Store silica gel correctly

We have seen boxes, buckets, and barrels of silica gel sitting at the packaging workstation, without lids or covers on the container. The silica gel absorbs moisture from the atmosphere when exposed to an open environment. It is therefore possible that the effect has worn off before it is ever placed inside the shipping container.

Correct storage of silica gel is critical. The simple solution is to securely close the original box with double plastic bags, but even then it will deteriorate over time. Our best suggestion is to invest in a plastic container with an indicator on top. Keep the lid on the silica gel container closed.

We offer a complete range of corrosion-inhibiting packaging and desiccants. In Norway, we have the agency for Zerust, the world's largest supplier of (VCI) poly-technology. Do you have a challenging corrosion prevention need, for example, shipping overseas or storage in corrosive environments? We can help you find the right solutions.

Also find articles on the Zerust blog.