The Curl Chemist explores popular low heat styling tools and reveals the the truth about the damage they cause.

Minimizing Damage

Lower temperatures

Multiple variables determine the type and extent of damage done by high temperature exposure, including the condition of the hair, the temperature being applied, and the duration of the exposure.  Hair in excellent condition will be more resilient and less likely to incur damage.

Outcomes are also greatly improved when lower temperatures are used and exposure times are minimized. However, evidence has been found that temperatures as low as 125°C (254°F) on a flat iron can induce formation of bubbles in the hair shaft.

The makers of Cool Way claim that the flat iron has a special sensor technology that enables it to automatically detect the moisture levels in the hair and to adjust the temperature for styling accordingly, with the additional promise that the temperature will never exceed 299°F.

This definitely is an advantage for this system over others that rely upon higher temperatures, but it is unclear whether it is sufficient to actually prevent damage to the hair. One of their claims, though, is that hair melts at 320°F, which is definitely untrue and should make the user cautiously skeptical regarding other claims made as well.

Thermal Protection Serums and Sprays

One popular method for reducing thermal damage incurred to hair when using heated styling tools is to apply specially formulated topical treatments designed to act as barriers against high temperatures.  Data has shown that these products can significantly reduce the damage done to hair by flat irons and curling iron and that they also improve water retention in the cortex of the hair.

Examination of the ingredient lists of these serums and sprays reveals that the most common active components of these products are silicones. Silicones provide a variety of benefits as thermal protection materials. Cyclopentasiloxane and cyclomethicone are used to aid in faster drying time, as they are volatile, small molecule silicones. They provide protection to the hair by driving off water more quickly and minimizing the likelihood of water boiling out of the hair shaft.

Higher molecular weight silicones such as phenyl trimethicone, dimethicone, and amine-functional silicones have very low thermal conductivity, which allows them to act as excellent insulators for hair against heat. They spread easily onto the surface of the hair and form films that encapsulate the hair and not only protect against heat very effectively, but also act to seal in moisture. By preventing water molecules from exiting the hair shaft, they effectively prevent formation of voids and bubble defects. While silicones are very good in this capacity, many people prefer to avoid them or use them only minimally.

Thermal protection serums do improve the outcome of using a flat iron, curling iron, or blow dryer set on high temperatures. However, they are usually extremely high in silicones or other non-water soluble polymers, and may cause problems with buildup or lead to limp tresses for some. They definitely could not be removed from the hair purely with a conditioner or mild shampoo.  So it is important to make certain that you cleanse your hair to remove these types of products once you are ready for your hair to revert to its natural state.

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Tonya McKay

Tonya McKay Becker is a curly-haired polymer scientist and cosmetic chemist whose academic and industrial research experience have provided her with expertise in the fundamentals and applications of polymer science and colloid chemistry. She has long had a fascination with the structure-property relationships of the complex solutions used in hair and skin care products, and how they interact with and impact these remarkable biological substrates. Ever curious, Tonya has dedicated herself for more than a decade to honing her expertise on the science of curly hair, how it differs from straight hair, and how product ingredients used on curly hair affect its health and beauty. Her passion for sharing this knowledge with others has led to her current career of educating people from all backgrounds who share an interest in this exciting field.