Metal corrosion rates do not double for each 10°C degrees storage test
temperature increase, thus higher storage temperatures do not accelerate
July 2018 Spray 25
metal corrosion rates.
perature testing is needed to determine formula thermal stability,
particularly when your products are marketed in regions with high
year-round or summer temperatures.
Higher storage temperatures are used to determine if products
are thermally stable and if thermal instability leads to corrosion of
package materials. However, it is recommended to:
• Not use higher storage temperatures to accelerate package
material corrosion rates in order to reduce test length;
• Use higher temperature storage to determine if there are possible
formula thermal instability issues that could cause package
material corrosion;
• Conduct tests at higher temperatures that reflect the actual
high temperatures for the regions in which your products are
marketed and
• Use higher temperature test lengths that reflect the actual
number of hours per year when the temperature is at or above
room temperature or some higher threshold temperature, such as
32°C.
Is it possible to reduce corrosion test time?
Attempting to accelerate package material corrosion with higher
temperatures or other means is not recommended. However, the
time needed for spray package corrosion testing can be reduced
by measuring corrosion with sensitive electrochemical corrosion
instruments.
Sensitive instruments measure polymer and metal corrosion
long before either can be seen with the unaided eye. However, the
appropriate measurement parameters, exposure times, analysis
protocols, sample size and protocols for interpreting the corrosion
data are all needed to obtain reliable results with electrochemical
corrosion tests.
Thanks for your interest and I’ll see you in August. Spray