st 32

SprayFeb14

Corrosion Corner 32 Spray February 2014 W. Stephen Tait, Ph.D. Chief Science Officer and Principal Consultant, Pair O Docs Professionals, LLC Perspective on corrosion issues facing spray packaging materials. H ello, everyone. Corrosion Corner is 13 years, 2 months old this month. Thank you and Spray Technology & Marketing magazine for your support and interest in this column over the years. I enjoy writing it, and look forward to writing Corrosion Corner for many more years to come. Corrosion is very expensive! The cost of spray package corrosion could include: 1. Corrosion testing, 2. Development of corrosion inhibitors, 3. Product recall when corrosion un- expectedly causes packages to leak, 4. Investigating package failures 5. Commercial or personal injury litigation Precise information on the corrosion costs to our industry listed above is difficult to estimate. The total corrosion cost in the U.S. is estimated to be 3.1% of the gross domestic product (GDP). The GDP for the U.S. was $1.69x1011 at the end of third quarter of 2013. Thus the 2013 corrosion cost to the U.S. was approximately 5.2 billion dollars at the end of last year’s third quarter. This estimation does not include the costs for recalls and litigation. Thus, the estimation is probably low and also does not include worldwide corrosion costs. Additionally, the loss of market shares that could occur from a recall or litigation is incalculable. Clearly, corrosion is a major concern to all industries, including ours. While much is known about the types of spray package corrosion, and how to test for corrosion, there are still many gaps in our knowledge about what causes spray package corrosion, and how to prevent and control it. From my perspective, there are ten major questions to consider when developing a new spray product or line extension to an existing product: 1. How does the type of formula water cause or contribute to aerosol container corrosion? 2. Will an anhydrous formula be contaminated with water at some point in the manufacturing and filling process? 3. Is there a critical concentration range for contaminant water in an anhydrous formula, above or below which the formula becomes corrosive? 4. How do the different types of fragrances (e.g., citrus, vanilla, etc.) cause or contribute to the corrosivity of the different types of spray formulas (e.g., aqueous, ethanol-water, emulsions, etc.)? 5. What initiates the various types of spray package corrosion, such as vapor phase, crevice and pitting corrosion? 6. Are there any safe formulas, ones that will not cause or contribute to aerosol container corrosion? 7. Are there specific formulating chemicals to avoid in a particular type of formula? 8. What causes package corrosion to be so seemingly random in its type and location inside a package? 9. What are the best-practices for spray package corrosion testing? 10. How should corrosion tests be designed to address variability of formula composition during manufacturing and package materials? This is quite a list! Reviewing it gives an appreciation for the breadth and depth of factors that influence whether or not spray package corrosion will occur with a given type of package and formula. Hopefully, this list also provides guidance on what areas of corrosion research need further development. Obviously, research produces more expedient and effective spray package corrosion prevention and control programs for companies using spray packaging for their products. We would be happy to teach our Elements of Spray Package (Aerosol Container) Corrosion short course at your R&D facility. Please contact rustdr@pairodocspro.com or visit www.pairodocspro.com. Please send your questions/comments/suggestions to rustdr@pairodocspro.com. Back issues of Corrosion Corner are available on CD from ST&M. Thanks for your interest and I’ll see you in March. Spray


SprayFeb14
To see the actual publication please follow the link above