Protect your gray or graying hair from sun damage.
The results showed that each UV absorber offered some protection to the hair, as the deterioration in properties was lessened measurably. However, the traditionally used OMC offered substantially less benefit than CATC and really only demonstrated marginal improvement over no treatment at all. It was found that the cationic UV absorber (cinnamidopropyltrimonium chloride) was more substantive to the surface of the hair after rinsing and was much more effective at maintaining the integrity of the hair for every single test. The molecule also had the property of being a mild conditioning agent, and added greater benefit to a formulation than the conventional OMC. CATC worked very well in oil-based leave-on sprays as well as shampoos, and the scientists concluded that it had real potential for helping prevent damage to gray hair (or any hair, for that matter) from the sun.
One important caveat is that it is not really possible to quantify the efficacy of sunscreens used in hair care products in the same manner as for sunscreens intended for skin protection. No standardized methods or tests exist for evaluation of sun protection for hair, and even if there were, consumer variability in application would render much of that type of data useless. Many cosmetic chemists completely dismiss any value to including UV absorbers in a hair product, despite the heavy marketing campaigns insisting otherwise. While I often share their skepticism regarding unlikely claims by manufacturers, this particular study showed that there does seem to be some benefit to formulating with cinnamidopropyltrimonium chloride (at least for the conditions in this particular study).
Scientists have long been interested in how the physical properties of gray hair differ from those of pigmented hair. Unfortunately, for those of us with gray or graying hair, research has shown that it is more susceptible than pigmented hair to various types of damage from UV radiation. Happily though, there does seem to be at least one UV absorber (and certainly others not covered in this study) that can help protect gray hair from damage in the sun. There are several products on the market that contain this ingredient, including Paul Mitchell's Color Protect Daily Conditioner, Soma Hair Technology's Colour Protect Shampoo and their Leave In spray, Kenra Platinum Smoothing Cream, and Aveda's Color Conserve Shampoo, to name a few. Not all of these products are necessarily compatible with the shampoo free method, but some are. Just make sure to check the ingredients list to be certain the product is right for you and your personal preferences. Products like this work best at minimizing incidental daily damage, in my humble opinion, so grab a cute straw hat or a pretty scarf to cover your hair when you plan to be in the sun for an extended time.