Yeah. That’s a thing.
It’s time to bust the myth of virgin hair…even if hair has never been processed via a salon service or at-home bleach, hair will have some level of damage. Exposure to UV radiation and air pollutants like cigarette smoke can result in significant oxidative stress on hair, skin, and scalp. This can affect structural properties of the hair fiber including fiber diameter, curvature, stretching, rigidity (brittleness), and lipid composition. A lot of science vocab to tell you: these alter the appearance and general manageability of the hair.
We always tell you not to panic, because the more you know, the more you can protect + revive hair to give it what it needs. Let’s dive into the science behind some of the chemical reactions that can happen to all hair, whether you’re frequenting a salon or not.
Meet nature’s OG bleach—we’re talking about the sun.
The sun emits strong energy in the form of UV rays. This energy can excite molecules in the hair to the point of unhinging an electron, which creates a free radical or reactive oxygen species (ROS).
Free radicals and ROS are highly reactive molecules with unpaired electrons capable of directly damaging structures like hair lipids and proteins. They can be created from external exposure to various oxidative stresses from the environment (as well as many chemical services). While living cells in skin have certain defense mechanisms in place to protect from oxidative stressors, the hair fiber, as a nonliving structure, does not.
Free radicals + ROS are agents of chaos in that they will react with things nearby, creating more radicals or breaking up molecules—including both the proteins and the lipids in hair. So what?
UV radiation can weaken the structural integrity of the hair fiber, resulting in degradation of amino acids and proteins, oxidation of internal and external lipids, destruction of melanin, and observed color fading, especially when humidity is high or hair is wet (but more on water later).
UV radiation induced hair damage is called photodamage. You may experience reduced strength, dryness, rough surface texture, loss of color, decreased shine, stiffness, and brittleness as a result of sun exposure damage. This ultimately leads to the degradation of hair pigments (melanin) and structure.
This type of damage is called oxidative damage and is how hair is professionally lightened: bleach will oxidatively degrade the melanin or pigments in hair, and incidentally the structural proteins too. This is how “surfer hair” happens. UV from sun + water + minerals facilitate the oxidative reaction which degrades melanin and bam you’re ready for the next surfing championship—and maybe a biotech hair mask to deal with the damage. Wink wink.
There’s also a lot of STUFF in the environment that can react with hair. Not to name names but pollution is kind of the worst. Metals and other contaminants like polycyclic aromatic hydrocarbons, or PAHs, can be found in water, air, or in the soot from factory pollution, urban dust, or automobile exhaust. These guys will catalyze (initiate or worsen) oxidative reactions, increasing the speed of naturally-occurring cortex degradation and cuticle delamination (i.e. removing the protective coating). They amplify the little oxidative explosions, which can create protein damage and loss all along and within the hair fiber.
now add water
Normally adding water is a good thing, like between cocktails or after a long workout, but adding water after your hair has undergone some of the damage above? Well…
Water is considered a chemical solvent—a liquid that provides a medium or substance for things to mull about in and interact. This process helps chemical reactions happen faster, so often as ambient humidity increases, or for hair that is wet, environmental chemical damage is given a boost.
Our scientist Meagan likes to use the example of starting the wave at a baseball game. When there are more people in the crowd, the wave can move smoothly along from place to place, coordinated by many people. Likewise, on the molecular level, the more water molecules, the easier chemical reactions (like that stadium wave) can proceed.
OK, so remember those free radicals + ROS we mentioned earlier? Increased decay of UV-induced radicals is enhanced at increased ambient humidity. Radical reactions occur faster due to a more liquid-like environment and resulting higher molecular mobility.
Certain fatty acids in wet hair produce hydroxy radicals upon exposure to UV radiation. The unsaturated fatty acids become peroxidized lipids, which break down themselves as well as degrade the proteins surrounding them. They produce holes within the cuticle layers, which exposes the cortex to then take damage.