Written on: August 1, 2025 by W. Stephen Tait
Hello, everyone. Corrosion is everywhere—and it’s expensive! Indeed, the estimated cost of worldwide corrosion services—testing, consulting, inhibitor/coating/laminated films for control and prevention—was a whopping $3.25 trillion in 2023.
For spray packaging, the risk of corrosion is always greater than zero and as high as 62%, particularly when there is no corrosion data for a new formula and/or derivatives of current formulas (line extensions). The liability for product recalls with litigation can range from $40 million to $183 million.
Two types of corrosion tests are available for spray packaging:
Figure 1 depicts the corrosion risks associated with each of these tests as a function of test length (Figure 1 is only valid when the appropriate test parameters are used).
The storage test curve in Figure 1 is from one-year old package examinations for pitting corrosion, for approximately 7,500 aluminum, tin-plated steel, tin-free steel and aluminum aerosol containers (approximately 750 to 1,000+ storage tests). The electrochemical test curve in Figure 1 was generated from over 1,500 direct comparisons between predictions from test results and actual package corrosion.
Notice in Figure 1 that results from a short storage test typically have higher risks than results from a long storage test. This is why I recommend conducting storage tests for at least one year before making a Go/No Go decision to commercialize a new product or a derivative product (line extension).
Figure 1 also illustrates that the risk for a properly-designed:
In other words, an electrochemical test can be completed in a significantly shorter time than a storage test with a corresponding lower risk.
Why corrosion risk is always a concern
Changes to a formula’s chemical composition can cause very large changes in corrosion behavior. For example, a new fragrance or a new surfactant in a non-corrosive base-formula sometimes results in a corrosive new derivative product.
Corrosion can unexpectedly appear with changes in the concentrations of formula ingredients either by design or from manufacturing batch-to-batch variations. For example, an inhibitor can lose its effectiveness when its concentration is either above or below the effective concentration range. In other words, an inhibitor could actually cause corrosion when its concentration is outside of its effective range.
Substituting formula ingredients from alternate suppliers could also cause unexpected corrosion in spray packaging. Also, contamination, such as water in anhydrous formulas, is a common cause for spray package corrosion.
Variability in formula ingredients, formula ingredient concentrations, package components and materials-of-construction also causes random corrosion in some instances.
Major elements of a corrosion control & prevention
A corrosion control and prevention program has multiple components as illustrated in Figure 2.
Corrosion testing is the linchpin of a comprehensive corrosion control and prevention program. Testing is used to determine formula compatibility with package components, metals and coatings. The risk of corrosion is approximately 62% when no corrosion tests are conducted on new formulas and derivative formulas, as indicated in Figure 1.
One doesn’t necessarily have to abandon a corrosive formula. In most instances, a corrosion inhibitor can be developed to transform a corrosive formula to a non-corrosive formula.
A maintained (i.e., actively updated) corporate knowledge and experience database helps avoid formula/package combinations and formula ingredients that have a high probability of causing spray package corrosion. Such a database can also reduce the number and length of corrosion tests in some situations.
“Knowledge + Experience” are shown in Figure 2 with a plus-sign (+) between them to emphasize that they are dependent on each other. Knowledge without practical experience, and experience without theoretical frameworks, are incomplete and will not result in useful, predictive professional practice. In other words, experience and knowledge work together to complete a comprehensive corrosion control and prevention program.
Understandably, corrosion control and prevention is typically not part of most corporate business plans and mission statements. However, product efficacy, quality and safety are!
Ignoring corrosion risk does not make it disappear and could lead to a major disruption of a business plan with a corresponding loss of income; this re-deployment of resources to determine the cause and find a solution could also delay other projects. Ignoring risk can also result in either an expensive product recall or litigation with subsequent potential loss of future sales when customers/consumers lose confidence in your products because of said recall or litigation.
In most instances, corrosion testing is significantly cheaper than an in-market corrosion failure. A comprehensive corrosion control and prevention program also prevents the loss of productivity and expense that accompany an in-market product failure (leaking packages).
Consequently, corrosion prevention and control should be a continuous process and not a one-time event.
Thanks for your interest and I’ll see you in September. Contact me at 608-831-2076; rustdr@pairodocspro.com or from our two websites: pairodocspro.com and aristartec.com. SPRAY
