September 2016 Spray 33 The variety of corrosion-causing factors, their number and possible combinations make predicting spray package corrosion difficult without corrosion data. Predicting package material corrosion rates without data is also not possible at this time. Consequently, corrosion testing is recommended for all new formulas and derivatives formulas and alternate packaging for existing formulas. A few corrosion-guidelines to consider when developing formulas or derivative formulas: • Don’t assume that small changes in the chemical composition of your formula won’t affect spray package corrosion • Don’t assume raw materials from different vendors have the same corrosivity or non-corrosivity • Raising pH is not a sure-fire way to reduce spray package corrosion • Propellant might also cause or contribute to spray package corrosion • The amount of contaminant water determines if an anhydrous formula is or is not corrosive • Don’t assume a given formula is not corrosive just because individual ingredients by themselves are not typically corrosive (synergy) • Don’t assume one type of spray package or spray package materials is more corrosion resistant than other types of packages and materials • Most of the time higher temperatures don’t accelerate corrosion We would be happy to teach our Elements of Spray Package (Aerosol Container) Corrosion short course at your R&D facility. We have also introduced the Corrosion Partnership Program, which makes our electrochemical corrosion laboratory, corrosion consulting and anti-corrosion technology conveniently available for your R&D program. Contact: rustdr@pairodocspro.com; 608-831-2076; www. pairodocspro.com. Back articles of Corrosion Corner are available from Spray. Thanks for your interest and I’ll see you in October. Spray
Spray September 2016
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