“Mood changing” hair dye uses stabilized thermochromic ink molecules that shift when heated or cooled, creating a surreal color changing special effect.

As the saying goes, “life is too short to have boring hair.” From Billie Eilish to the Trolls, big hair energy is everywhere. But what look to choose? So many colors, so many styles, so many moods.

If your idea of “not boring” changes from minute to minute, color changing hair dye has you covered. Curious about dancing around the hair spectrum? Fantasy becomes reality in our guide to expressing yourself with color changing hair dye.

Person with brightly-colored hairShare on Pinterest
Illustration by Maya Chastain

Thermochromic hair dye is a temporary hair color product that changes hue with even a subtle shift in temperature. Your coif literally becomes your real-time canvas depending on the temp. The tint will change with heat or cold, so a curling iron, some warm fingers, a cool breeze or a snowball to the head will all cause a colorful reaction.

Best part: no commitment. It’s even less permanent than semi-permanent hair dye. Some brands claim to rinse out completely with one hair wash, so color changing hair dye isn’t technically a dye. It’s what’s called an “overlay,” or a layer of color that sits on the surface of your hair strand. Sort of like makeup on your skin.

But, be sure to check that label. If the brand says “permanent” or “semi-permanent,” you’re dealing with color that’s going to stick around for a bit.

The secret to color changing hair dye is thermochromic pigment, or color that changes with temperature. Remember those Hypercolor t-shirts that were popular back when Terminator 2 dominated the box office? Same premise. It’s the same tech that lets you know when your AAA battery is kaput or your beer is cold enough to enjoy.

Color change pigment is composed of molecules whose bonds react to temperature, changing their shape and stability when heat is added or taken away. When the temps change, the active molecules react. The dye molecules reflect more light when warmer and absorb more light when cooler. Voila! Color change “magic.”

At first, color change hair dyes were available only at salons. But a few companies now offer at-home kits for you prospective hair Picassos. Specifics might change from brand to brand, but here are the general steps for applying color changing dye:

  1. Wash your hair and towel it dry. Avoid conditioners or any products that might get between the dye and the hair.
  2. Put on protective gloves and something to protect your clothes, like a smock, a robe, or a towel.
  3. Line your scalp with a light layer of petroleum-based ointment to prevent the dye from running onto your face or into your eyes. This reduces the chance that you might experience unexpected irritation.
  4. Since this might get a little messy, pick a place to apply the dye that you wouldn’t mind cleaning up. (Bathroom? Garage? Back yard?)
  5. Use the sponge applicator that comes with the dye or a fresh makeup sponge to apply the dye. Simply dip the sponge into the dye and brush onto your hair as desired. Unleash your inner artist!
  6. Use an angled tint brush to help spread the color evenly through your hair. Generally speaking, lighter colored hair will show more vibrant results, darker hair will have a more subtle effect. (For those with darker hair who want to turn up the pop factor, consider pre-lightening your hair or even using lighter colored hair extensions to get a more obvious result.)
  7. After you’re done applying, blow-dry your hair on a medium setting. This stuff is a little sticky, so a final blow dry will help chill out that tacky feeling.

Bonus tip: Use a stencil when applying the color with a sponge to create a bolder statement.

Now for the Harry Potter moment! Any change in temperature will activate the color changing radness. The easiest and quickest way to get results is to use a hot hair tool like a flat iron, a curling iron or a hair dryer. You can use your tool (carefully!) sort of like a virtual crayon, applying the heat to specific spots on your hair will create trippy two-toned effects.

Like those mood rings that were all the rage around 1975, your body can also provide the heat. In theory, color change hair dye could change color when you blush. But it might be easier to let your fingers do the work. Smack those hands together and rub them really fast (like Mr. Miyagi taught you). Now see what happens when your hot digits interact with your thermochromic hair.

When you take away the heat, the color changes again. What takes away heat? Anything cold! (Do we sound like your high school chem teacher?) Grab an ice pack from the freezer and see what happens when you touch it to your thermally dyed hair. Even a blowdryer set to cool mode will work.

Remember you can’t always control when or where the color will change when you use color changing hair dye. If you step onto a sunny balcony after sitting in an air conditioned office, the color will change. If you go from a steamy subway platform into a frigid subway car, the color will change. Your “mood hair” will have a mood of its own when exposed to changing temps.

Although dying your hair is considered safe, there are potential risks to using anything that might irritate your scalp. It’s important to make sure that your scalp is free of any wounds, sores or irritation before using any kind of hair dye. Adding dye to an area of your body that is already in trouble will only add more trouble.

Color changing dye is temporary, but prepping your hair by bleaching or highlighting too often can cause damage to your locks. Over-dyeing or using anything that irritates the skin on your scalp could lead to potential hair loss. One study suggests that you shorten your dyeing session by 25% so that you can lower your exposure to anything that might be harmful to your skin.

Also, when playing around with your prismatic locks, go easy on the heat. Flat irons and curling irons can fry your hair, so it might be a good idea to use a heat protectant spray. Don’t let playing around with color changing hair dye mess up your healthy hair care routine. But if you feel the fry, there are ways to help care for damaged hair.

And remember, it’s important to use high-quality hair products that don’t contain potentially harmful chemicals. Read those labels and know what you’re putting on your body. Again, anything that irritates your scalp is no good. Go for a product that has as few irritants as possible.

For a coif that changes on a dime, check out color changing hair dye. This temporary color overlay changes with temperature to create shifting hair color right before your eyes.

Relatively simple to apply, color changing hair dye goes on almost like makeup. Simply apply to freshly cleaned hair with a makeup sponge or angled tint brush then blow dry on low to clear out some of the sticky feeling of the dye.

You can enjoy playing around with your favorite heat tool or ice pack to create some prismatic fun or simply let the elements around you dictate the change. Your hair is your canvass and your imagination is the only limit.