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The Mysteries of R&D, Part II: Why Do They Always Say “Not Ready Yet”?
By: Art Rich, PhD
Posted: November 5, 2010, from the November 2010 issue of GCI Magazine.
page 2 of 6
Stability for Cosmetics: This test is a predictive assessment of product shelf life. While the actual program conditions vary from company to company, a brief, general description here will be sufficient.
Samples are placed at one or two elevated temperatures, usually 45°C and 37°C, for a period of up to three months to provide for an accelerated assessment of shelf life. Evaluation at these temperatures, when compared to a sample at room temperature, will determine how the product will behave during aging. There should be little or no change during storage at the highest temperature for one month. The lower temperature samples can be observed for a longer period (three months).
Samples are also placed through three freeze-thaw cycles, where the sample is frozen for 24 hours and allowed to return to room temperature for 24 hours. This procedure is repeated two additional times. This test is usually run on emulsion systems to see if they will remain homogeneous through the three cycles.
Clear liquids (shampoos, liquid cleansers, etc.), in addition to the this testing, are evaluated at refrigeration temperature to see if they remain clear.
Samples are also exposed to light to see if there is fading or a color change. Exposure to natural light under specified conditions is usually for a period of one month. Artificial light testing can be done instrumentally in 24 hours.