Does Using a Heat Protectant for Hair Actually Prevent Damage?

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Maybe you went through a phase during when you flat ironed your hair (bangs included) to a crisp, then decided to change your ways. Or perhaps you're on a hair health kick and want to learn about how hair masks, oils, and the like can impact your strands. Either way, you've probably wondered about how to find the best heat protection spray for hair — and whether the products are worth buying in the first place.

Before you add yet another hair product to your rotation, find out whether using a heat protectant spray for hair can actually shield your hair from the wrath of hot tools. Here, Trefor Evans, Ph.D., director of research and institute fellow at Textile Research Institute Princeton, is breaking down how heat affects hair, and whether or not heat protectant products can prevent the damage.

Q: I use a hair dryer daily and am worried about damage. How can I find the best heat protectant for hair and do they even do anything to begin with?

A: Using a heat protectant for hair can mask damage from heat application but won't prevent the effects in the first place, according to Evans. While it's impossible to prevent damage from using hot tools, you can minimize the effects by sticking to a low-temperature setting when heat styling your hair, he says. If you're trying to weigh out the pros and cons of continuing to use hair dryers or irons in your routine, it's helpful to consider how heat affects your strands in the first place.

What are the downsides of having heat-damaged hair?

Anyone who's grazed their neck with a curling iron is well aware that hot tools can get, well, hot. "A hair dryer might get your hair to about [176° F], and quite frankly, that's no big deal at all," says Evans. "The problem comes in when you start to talk about the styling tools, [e.g., curling irons and flat irons] which can often go to incredibly hot temperatures." The tools often reach 450° F, a temperature just slightly below the theoretical decomposition of hair (464° F), he says,

"Once you get above about [392° F] maybe a little bit higher, that's when you're getting into that danger area," says Evans. "If you bake bread, you normally turn the oven onto about 450° F. That's, the temperature that your flat iron is going to." While plenty of hot tools have lower temperature settings, in practice a lot of people prefer to use higher temperatures for more effective styling, he notes.

As for how repeatedly applying heat can impact the look and feel of your hair, strands' tensile strength (which affects how much hair can be stretched before breaking) can drop off, and breakage can occur, according to Evans.

Is using a heat protectant for hair useful?

Despite the name, even the best heat protectant for hair won't prevent damage, according to Evans. "A cosmetic product deposits a single layer on the surface of the hair, to help with manageability," he says. "Is a thin layer of a coating going to protect your hair from 450° F? It's possible you'd have to coat your hair with space shuttle tiles to protect it against that sort of temperature." Long story short, the products don't prevent damage.

That said, a heat protectant spray for hair isn't useless. "What these products do is mask the effects of the damage, so the damage is still there, but [you] don't perceive it," says Evans. "These heat protection products are essentially conditioners." That means that they form a lubricating layer on your hair, preventing snagging when you comb through your hair and minimizing breakage, he says.

The damage is unavoidable, but you can minimize the negative effects of hot tools by using lower heat settings, according to Evans. Incorporating a suitable conditioner into your routine to address the inevitable damage is also key, he says. "The right level of conditioning is really dependent on your hair type," he says. "If you've got long, thick, curls, then you can tolerate quite a high level of conditioning." However, choosing a product with a high conditioning level or applying too much product can weigh your hair down if you have more fine hair, he says. As a rule of thumb, you want to condition your hair as much as your hair type can get away with without weighing your hair down, he says.

If you suspected that achieving complete heat protection for hair by misting on a product sounded too good to be true, you were right. If you're not ready to give up hot tools, though, sticking to a low-temperature setting and adequately conditioning your hair can benefit your strands.

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