About the Author

W. Stephen Tait
W. Stephen Tait
Dr. Stephen Tait is the Chief Science Officer and Principal Consultant for Pair O Docs® Professionals L.L.C. He has 40 years of experience with all aspects of anti-corrosion technology, and investigating failure of metal structures. He has developed numerous corrosion prevention and control programs for food and aerosol containers, vacuum-deposited coatings on glass, consumer electrical appliances, chemical processing equipment and chemical reactors, gas refinery cooling towers, and both commercial and consumer transportation vehicle coatings. Dr. Tait is an industry leader in electrochemical corrosion testing, and the application of reliability engineering to packaging for consumer products. He holds eight U.S. and foreign patents on corrosion measurement equipment, corrosion inhibitors, a device for monitoring crevice corrosion, and is the inventor of the Tait Cell, GEN2, GEN3 and GEN4 Multi-cells, and the Flexi-cell for electrochemical testing. His unique combination of education in metallurgy, chemical engineering and chemistry, plus his extensive experience and knowledge on all aspects of metal package construction, filling, corrosion, and modes of failure make him an ideal expert witness for litigation involving metal package failures. Dr. Tait developed and managed a world-class corrosion research and testing laboratory while at S. C. Johnson. This laboratory included two satellite laboratories in Europe and China. Test results from these labs allowed low-risk rapid introduction of new products and prevention of both packaging and equipment failure by corrosion. Earlier, with Petrolite Corporation (a specialty chemical manufacturer for the petrochemical industry) he developed corrosion prevention and control programs for the petrochemical industries. Dr. Tait, an accomplished technical author, wrote the textbook on electrochemical corrosion testing. Over 1300 copies of his book have been sold worldwide to industries, universities and government laboratories since its publication in 1994. He writes Corrosion Corner, a monthly column for Spray Technology & Marketing magazine, and has authored and presented over 80 technical papers and chapters in books. He also is a peer reviewer for many of the technical journals in his field. His teaching experience spans over 40 years and includes traditional university classroom and continuing professional education courses in chemistry, chemical engineering, corrosion and materials engineering, corrosion science and prevention. He was also an adjunct full professor at the University of Wisconsin-Milwaukee from 2000 to 2003. Dr. Tait is certified by NACE International as a Corrosion Specialist. He is one of eighteen specialists worldwide who are certified by that organization in chemical treatment of corrosion (formulation of corrosion inhibitors). He is a member of NACE International; the Electrochemical Society; and ASM International. EDUCATION: Ph.D., Materials Engineering, University of Wisconsin-Milwaukee MS, Chemical Engineering, Washington University in St. Louis BA, Chemistry, University of Missouri-St. Louis EXAMPLES OF PATENTS U. S. Patent 8,344,056: Spray Texture Material Compositions, Systems, and Methods with Anti-Corrosion Characteristics U. S. Patent 6,501,286: Multiple Reference Electrode Array for Measuring Open Circuit Potentials in Artificial Crevices U. S. Patent 4,240,925: Pitting Corrosion Inhibitors U. S. Patent 4,668,293: Phytate Corrosion Inhibitor System U. S. Patent 4,668,507: Corrosion Resistant Insecticidal Composition U. S. Patent 4,720,382: Inhibiting the Corrosion of Hair Conditioning Compositions EXAMPLES OF PUBLICATIONS An Introduction to Electrochemical Corrosion Testing for Practicing Engineers and Scientists, Pair O Docs Professionals L.L.C., Madison WI (1994) Corrosion Corner, a monthly column on aerosol container corrosion published in the Spray Technology and Marketing magazine (December 2000 to present). W. S. Tait, Corrosion Prevention and Control of Chemical Processing Equipment, Chapter 27 in the Handbook of Environmental Degradation of Materials, William Andrew Publishing, Norwich, NY (2005) W. S. Tait, Dielectric Properties, Chapter 24 in Desk Reference of Polymer Characterization and Analysis, Oxford University Press, Cary, NC (2003) W. S. Tait, Using Electrochemical Measurements to Accurately and Quickly Estimate Coating and Polymer Film Durability, J. Coatings Technology, (Journal of Coatings Technology, 75 (924), 2003) W. S. Tait, Make Your Corrosion Data More Reliable, Corrosioneering, May 2002 W. S. Tait, Increase Your Confidence in Corrosion Data, Materials Performance, March 2001 W. S. Tait, Reliability Engineering: The Commonality between Airplanes, Light Bulbs,and Coated Steel, Service Life Prediction of Organic Coatings: A Systems Approach, edited by D. R. Bauer and J. W. Martin, American Chemical Society Symposium Series 722, American Chemical Society, Washington, DC (1999). W. S. Tait, Using Reliability Statistics to Estimate Metal Container Failure Levels from Censored Tests, Organic Coatings for Corrosion Control, edited by G. P. Bierwagen, Chapter 6, pp. 58-68, Symposium Series 689, American Chemical Society, Washington, DC (1998). W. S. Tait, Aerosol Container Corrosion and Corrosion Testing: What is the State of the Art? Spray Technology, (September 1997). R. S. Lillard, J. Kruger, W. S. Tait, and P. J. Moran, Using Local Electrochemical Impedance Spectroscopy to Examine Coating Failure, Corrosion, 51(4), pp. 251-259 (1995) W. S. Tait, Coping with Errors in Impedance Spectra from Coated Metals, Journal of Coatings. Technology, 66(834), pp. 59-61 (1994) W. S. Tait and K. A. Handrich, Cation Enhancement of Internally Coated Metal Container Corrosion Failure, Corrosion, 50(5), pp. 373-377 (1994) W. S. Tait, K. A. Handrich, S. W. Tait, and J. W. Martin, Analyzing and Interpreting Electrochemical Impedance Spectroscopy Data from Internally Coated Steel Aerosol Containers, in ASTM STP 1188, pp. 428-437, American Society for Testing and Materials, Philadelphia, PA (1993)
Articles by W. Stephen Tait
Hello everyone. In last month’s Corrosion Corner, I identified and discussed the multiple microenvironments that occur inside spray packaging and spray packaging components. Microenvironments are why spray package corrosion is so complex and unpredictable without…
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Hello everyone. How a spray package is constructed, its materials of construction and the chemical composition of a formula all interact to determine if corrosion will occur and how fast the corrosion will proceed to…
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Hello everyone. Water is often referred to as being the closest thing to a universal solvent. It dissolves a wide range of formula ingredients and dissolves into a wide range of formula chemicals. For example,…
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With SUSAN WHITWORTH Tait, Ph.D. Executive Director & CFO, Pair O Docs Professionals, LLC     Hello, Everyone. We again have a paradox—both docs from Pair O Docs Professionals LLC. are authoring this month’s edition…
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Hello, Everyone. We have a paradox—both docs from Pair O Docs Professionals LLC are authoring the June and July editions of Corrosion Corner. Those of you who have worked with Pair O Docs know Sue…
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Hello, everyone. I recently read several news articles about a few sunscreen chemicals that might have alleged adverse environment effects; I also read of a new U.S. Food & Drug Administration (FDA) proposal for sunscreen…
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Hello, everyone. Spray package corrosion is typically not at the forefront of most people’s thinking. However, everyone on a metal spray package development team should tacitly know there is always a risk of spray package…
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Hello, everyone. There have recently been several articles and editorials about probiotics in spray formulas (see the editorial in the December 2018 issue of SPRAY). If you haven’t been following articles about probiotics, they are…
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Hello, everyone. Last month I discussed a first-principles empirical equation for predicting if corrosion could occur. However, the equation only indicates if corrosion might occur and provides no information on how fast corrosion will occur…
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Hello, everyone and welcome to the New Year. There are 14 possible types of corrosion in the most widely used spray package components as illustrated in Figure 1 and Figure 2. These two Figures are…
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Hello, everyone. All spray package materials are susceptible to corrosion. There are a variety of materials used to fabricate spray packages: Metals, such as aluminum, steel and tinplated steel (ETP) Aluminum spray package components are…
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Hello, everyone. Last month, we began a discussion about how polymer barrier properties can be broken down by permeation and higher storage test temperatures. This month, we’ll complete the discussion by reviewing how polymer glass…
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Hello, everyone. Synthetic polymers, such as epoxies, Micoflex, polyethylene terephthalate (PET) and laminate films are used for spray package coatings as barriers between a formula and the underlying metal or metal foil. Polymers have voids…
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Hello, everyone. It is often assumed that a higher storage temperature will increase the rates of polymer and metal corrosion and thus reduce the time needed for corrosion testing. For example, it’s common to assume…
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Hello, everyone. It’s commonly believed that coatings and laminate films are barriers between a spray package metal or metal foil and your formula and that a barrier is needed to prevent corrosion of the metal…
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Hello, everyone. Last month, we discussed the first three of six common questions about spray package corrosion; we’ll tackle the final three questions this month. Anhydrous formulas are immune from corrosion—true or false? Kind of…
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Hello, everyone. This month I’m starting a six-question spray package corrosion quiz. A quiz? Hold on, don’t panic! There’s no grade and the quiz won’t be part of your next performance review—it’s merely intended to…
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  Hello, everyone. Spray packages allow consumers to easily dispense a controlled amount of product to a wide range of areas. Corrosion is an issue for all types of spray packaging and packaging materials. However,…
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Happy new year, everyone. In the September 2017 edition of Corrosion Corner, I began a five-part series on the corrosive behavior of the various metals and coated metals used in fabricating spray packages and valves.…
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Hello, everyone. In the September edition of Corrosion Corner, I began a five-part series on the corrosion behavior of the various metals used to fabricate aerosol containers and valves. This month I’ll discuss the corrosion…
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Hello, everyone. Last month we had Part II of a five-part series on the metals used to fabricate spray packaging. This month, we continue with a discussion of tin-free-steel, more commonly referred to as TFS.…
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Hello, everyone. Last month, I began a five-part discussion on the metals used to fabricate spray packages and packaging components (I added another part to include laminated metals). The corrosion resistance for the different packaging…
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Hello, everyone. Storage temperatures above room temperature are often used to accelerate corrosion and thus reduce the length of time needed to determine the corrosion compatibility of products with packaging materials. Are there technical origins…
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Hello, everyone. Last month I began a detailed discussion on a figure that contains the risk for conventional storage corrosion tests as a function of test time and risks associated with electrochemical corrosion tests. This…
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Happy new year, everyone. The May 2016 through August 2016 Corrosion Corners have a series of discussions on corrosion risks with spray packaging, how the cost for corrosion failures is significantly higher than corrosion testing,…
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Hello, everyone. In the May–July 2016 Corrosion Corners, I discussed corrosion risk and how the cost for corrosion failures is significantly higher than corrosion testing. Corrosion prevention and control is a continuous process and not…
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Batteries, Electrolysis, Electrolytic Corrosion, Electro galvanic Corrosion, Galvanic Corrosion and Electrochemical Corrosion. Hello, everyone. A number of terms are used to describe or explain spray package corrosion. The most common terms are: Batteries Electrolysis Electro…
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Hello, everyone. Modern spray packages are often fabricated with two or more different metals, making galvanic corrosion possible. Galvanic corrosion is a form of localized corrosion where one metal causes the other different metal to…
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Hello, everyone. Spray packages and spray valves are fabricated from a variety of materials, such as: Uncoated aluminum Polymer laminate film(s) on aluminum foil Polymer coating on aluminum Uncoated tinplated steel Polymer coated tinplated steel…
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Happy New Year, everyone. The chemical composition of a formula determines if corrosion will occur, where it will occur and how fast corrosion proceeds through the package metal to cause leaking or how fast the…
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Hello, everyone. Three ingredients are needed for metal or coated metal corrosion: A metal or metal alloy—with or without a coating Water—either as a contaminant or as a component of your formula Ions and/or molecules…
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Hello, everyone. Time is typically short for commercial development of new products and derivatives of existing products (e.g., an existing product with a new fragrance). However, corrosion takes time a) to initiate, b) to grow…
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Hello, everyone. One of the most frequent questions that I’m asked is, “When is corrosion testing required?” Chapter Seven of our Elements of Spray Packaging short course discusses various types of corrosion tests and when…
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Hello, everyone. I began a series on spray packaging material defects and their relationship with corrosion in June. The June and July Corrosion Corners covered defects in polymer and tinplate coatings, laminated film bags and…
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Hello, everyone. Last month, I began a series on material defects in spray packaging and the relationship between these defects and corrosion. We completed a discussion on the more common defects in aluminum aerosol containers.…
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Part I: Traditional aluminum aerosol containers Hello, everyone. There is no such thing as defect-free spray package materials. Thus, there are always potential concerns as to whether or not defects will contribute to or cause…
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Hello, everyone. Every year, we receive multiple requests to determine the cause of spray package failure from corrosion (leaking packages). In many of these instances the spray product was commercialized after a few months (e.g.,…
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Hello, everyone. In the February 2015 edition of Corrosion Corner I provided an overview of the relationship between spray package commercial life and spray package service life. These two lifetimes can be used to determine…
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Hello, everyone. Last month’s Corrosion Corner provided an overview of the relationship between spray package commercial life and spray package service life. These two lifetimes can be used to determine if corrosion is too severe…
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Hello, everyone. Last month I discussed several corrosion and statistical technical terms that are relevant to spray package corrosion. This month I’ll expand that discussion by focusing on the relationship between commercial life and service…
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Happy new year, everyone. Corrosion science and engineering, like all technical fields, has its own jargon. I thought we’d start out this year by defining those corrosion terms and a few statistical terms that are…
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Hello everyone. Is corrosion-free spray packaging a realistic expectation? What can happen when a spray package corrodes? This month we’ll examine the various scenarios that could occur when a formula causes spray package corrosion, and…
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Hello, everyone. Metal pitting corrosion causes perforation and leaking of spray packages. What is the minimum number of elements needed to initiate corrosion and sustain pitting corrosion of the metals used for spray packaging? Only…
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  By W. Stephen Tait, Ph.D., Pair O Docs Professionals, LLC Hello, everyone. There are essentially up to two phases in a spray package: a liquid phase (could be your product plus the propellant) and…
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Hello, everyone. In late July, I received a newsletter from one of our affiliate chemical testing laboratories that discussed the Ban Poisonous Additives Act (H.R. 5033) introduced in early July in the U.S. House of…
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Hello, everyone. Water plays many different roles in the corrosion of spray package materials. For example, water molecules: Could be a corrosive formula ingredient Transport corrosive formula ingredients to the package metal Move ionic charges…
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  Hello, everyone.  Internal coatings in spray packages are not barriers between the package metal and your formula.  Laminate films on metals are typically much thicker than coatings.  However, laminate films are also not true…
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Hello everyone. I used the two most difficult questions to answer about spray package corrosion as the title for this Corrosion Corner. An example for the first “Why” challenge is: you have a static storage…
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Hello, everyone. The metals used to fabricate spray packages include: Steel alloys (both tinplated and tin-free) Aluminum alloys Polymers Laminated aluminum alloy foils Stainless steel alloys Stainless steel is the least visible of all packaging…
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Hello, everyone. Corrosion is the degradation of materials from either a chemical or electrochemical reaction. Chemical corrosion is typical of polymer materials, such as coatings and laminate films. Electrochemical corrosion is typical of metals and…
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“What causes pitting corrosion?” is a very common question for spray packaging. There are multiple factors that could cause pitting corrosion in spray packaging. Let’s start the discussion by defining pitting corrosion. Corrosion Basics: Definition…
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  The surfaces of spray package materials are far from perfect. The metal-making process, the processes used to fabricate metal containers, coating application processes and the foil lamination formation process often produce surface anomalies that…
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  There is often push-back on the need for corrosion testing, particularly when market timetables are short. The no-corrosion-data risk is approximately 62% that some type of corrosion will occur in traditional aerosol containers. In…
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  Crevice corrosion is a type of localized corrosion that occurs in the small gap between two pieces of overlapping metal. Crevice corrosion could be general corrosion, pitting corrosion or both. Crevices can be found…
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  Hello everyone. Tinplated steel for both food containers and spray packaging is fabricated from steel sheet that has a very thin layer of tin on both sides of the sheet. The tin is electroplated…
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  This month I thought it would be interesting to provide a list of corrosion tidbits that are relevant to spray package corrosion. I’ve alphabetically arranged the various tidbits into several categories. Analyzing & interpreting…
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Aluminum spray package metals, internal coatings and laminate films are far from perfect (I will hereafter refer to coatings and laminate films as polymers). Indeed, the polymers are not always continuous (i.e., they have holes)…
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  Corrosion is often thought to be a very simple process. However, most types of corrosion are very complex, multiple step processes. For example, the equation for corrosion of aluminum in hydrochloric acid is: The…
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  Hello everyone. There are several types of metals used to fabricate spray package components. There’s also a common corrosion myth that aluminum is more corrosion resistant than steel. Let’s briefly review the types of…
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  Hello everyone. I’m often asked how corrosion starts in spray packaging. The corrosion of spray packages begins in so many different ways that a comprehensive discussion is beyond the scope of Corrosion Corner. However,…
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Hello everyone. One of the most difficult questions to  answer about corrosion is why it’s so random. For example, you have a static storage test on a new formula or line extension, and you open…
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Hello everyone. There are many ways that a spray package could fail (e.g., malodorous product, leaking or no longer sprays). However, the most likely mode of spray package failure is from localized corrosion. Localized corrosion…
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Happy New Year everyone. Testing spray packages at several different storage temperatures is a common practice. The typical objectives for using different temperatures are to determine product stability and product-package compatibility for the range of…
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Hello everyone. A lot of people find corrosion very exciting. For example, your marketing manager probably gets very excited about corrosion if it jeopardizes the timetable for a new product. In contrast, corrosion is exciting to engineers and scientists…
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Hello everyone. Water is often referred to as being the closest thing to a universal solvent. It dissolves a wide range of formula ingredients and dissolves into a wide range of formula chemicals. For example, inorganic salts and…
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Hello everyone. Free liquid water is needed for metal corrosion and polymer corrosion to occur. Anhydrous spray formulas (or solvent formulas) are typically regarded as being corrosion-proof because they are essentially water-free. However, there are instances when a non-corrosive…
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Hello everyone. One of the most persistent myths in corrosion is that chloride ions cause pitting corrosion for all metals and coated metals. The myth about chloride ions and corrosion most likely originated with the pitting corrosion behavior of some stainless steel alloys in…
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Hello everyone. Spray package metals, polymer laminate films and internal polymer coatings are all susceptible to corrosion. In this month’s Corrosion Corner, I’ll review several of the general attributes of spray package corrosion and the adverse effects corrosion has on both product efficacy and spray package…
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