When a VCI Test Is Not Enough

The NACE Standard TM0208 Vapor Inhibition Ability (VIA) test, commonly called the VCI test or VCI jar test, is a valuable tool for evaluating the corrosion protection performance of vapor corrosion inhibitor technology. It allows researchers to quickly compare the vapor phase corrosion protection of different VCI packaging materials and chemistries.

However, while a VCI test provides rapid insight into vapor corrosion inhibition performance, it does not always represent the complete corrosion protection system used in real applications.

For example, the standard VCI test primarily focuses on vapor-phase protection. It does not fully evaluate other factors that influence corrosion protection, such as packaging barrier properties, coatings, or directly applied rust preventatives. In addition, the VCI jar test has limitations when testing products such as sprayable greases, rust-preventative oils, or other applied corrosion inhibitors.

Because of these limitations, corrosion specialists often rely on additional testing methods to understand how corrosion protection systems perform in real environments.

Environmental Chambers Used to Supplement a VCI Test

To supplement the standard VCI test, ZERUST® uses several types of environmental testing chambers to evaluate corrosion protection solutions under controlled conditions. These chambers allow us to simulate harsh environmental factors that parts may experience during storage or transportation.

Our testing laboratory typically uses three main types of chambers:

• High humidity chambers
• Salt fog chambers
• Temperature and humidity cycling chambers

These environmental chambers enable longer-term studies and more detailed comparisons of corrosion protection systems.

In addition, they allow engineers to test a wide range of metals and protection methods. For example, engineers prepare panels from standard 1010 steel, aluminum alloys, or aerospace-grade metals and expose them to controlled environmental conditions while protecting them with different VCI packaging materials or corrosion inhibitors.

Even more importantly, these chambers allow testing systems that closely resemble real customer conditions. A component may first be exposed to machining fluids used in the customer’s production process. It can then be packaged in different VCI packaging materials before entering the environmental chamber for evaluation.

This type of testing provides a more realistic assessment of corrosion protection than a simple VCI jar test.

The Tradeoff: When a VCI Test Requires More Advanced Testing

While environmental chamber testing offers valuable insight, it also requires significantly more time and preparation than a traditional VCI test.

Many tests are run for hundreds of hours inside a chamber. In addition, because these systems often include multiple variables such as metal type, coatings, fluids, and packaging materials, the testing matrix can become complex. As a result, setting up and monitoring these experiments requires careful planning.

Despite the time investment, the results are extremely valuable. Chamber testing allows corrosion engineers to approximate real-world environments in an accelerated and controlled manner. This deeper level of testing also evaluates barrier properties of films and coatings, which are not captured by standard VCI jar testing.

Salt Spritz Testing Beyond a Standard VCI Test

One example of accelerated corrosion testing used alongside a VCI test is the salt spritz test performed in humidity chambers.

During this test, metal panels are sprayed with a methanol solution containing a known concentration of sodium chloride. This introduces a controlled amount of corrosive contamination onto the surface of the panels.

The purpose of the test is to evaluate how effectively a corrosion protection system can neutralize or tolerate chloride contamination.

Compared to many chamber tests, the salt spritz test is relatively fast. Most evaluations take only three to four days from sample preparation to completion. However, this test works best when the corrosion inhibitor has the ability to handle chloride contamination, which is not the case for every corrosion protection chemistry.

Cycling Tests That Complement a VCI Test for Shipping Conditions

For products that are not designed to neutralize salts, corrosion specialists often rely on temperature and humidity cycling tests.

These tests follow conditions similar to the IEC 60068 environmental standard. The chamber cycles between periods of higher humidity with lower temperature and periods of lower humidity with higher temperature.

This cycling pattern is particularly useful for simulating transportation and storage environments. For example, packaged parts may not be exposed to outdoor weather, but they may still experience daily temperature swings during shipping or storage.

When combined with a VCI test and salt spritz testing, these cycling tests help confirm long-term corrosion protection and the ability of packaging systems to handle environmental changes.

Comparative VCI Test Methods for Meaningful Results

In most cases, corrosion testing is performed using comparative methods. This means test panels are evaluated alongside several control materials.

Typical controls include:

• Plain polyethylene film
• Known high-performing VCI films
• Competitive corrosion protection materials

This type of “horse race” testing allows engineers to compare multiple products under identical conditions. As a result, it becomes easier to understand how a specific corrosion protection solution performs relative to other options.

However, it is important to remember that even advanced environmental testing has limitations.

Why VCI Test Results Do Not Always Predict Real Performance

One common question customers ask is how laboratory test hours translate into real-world protection time.

In reality, corrosion test chambers create highly controlled conditions. For example, they use deionized water and maintain tightly controlled temperatures and humidity levels. These conditions often represent a worst-case scenario rather than a typical real-world environment.

Similarly, when chloride contamination is introduced during testing, laboratories typically use pure sodium chloride. Real-world contamination is rarely this consistent or concentrated.

Because of these factors, laboratory testing hours cannot be directly converted into real-world corrosion protection timelines.

Instead, the purpose of these tests is to compare corrosion protection systems under repeatable conditions.

Why Environmental Testing Is Important Alongside a VCI Test

Even with its limitations, environmental chamber testing remains an essential part of corrosion protection development.

A standard VCI test provides quick insight into vapor phase corrosion inhibition. However, environmental chamber testing provides a much deeper understanding of how complete protection systems perform.

The data collected from these tests supports product development, quality validation, and technical service work. As a result, corrosion specialists can design packaging systems that perform reliably in real industrial environments.

By combining the speed of a VCI jar test with the depth of environmental chamber testing, ZERUST® engineers can deliver corrosion protection solutions that meet demanding real-world conditions.

Mitchell Fillbach

Mitchell Fillbach serves as a Research Scientist and Process Engineer at ZERUST®, where he applies a decade of industry expertise to product development and process improvement. With a focus on advancing corrosion prevention technologies and optimizing production methods, Mitchell works across research and engineering projects to ensure innovative, reliable, and efficient solutions. His strong technical background and commitment to continuous improvement contribute to ZERUST®’s mission of delivering high-performance, sustainable corrosion protection to global industries.

All Articles