If you've dyed your hair rainbow colors [1], you know that there are a few rules to follow [2] when it comes to mane maintenance. Wash your strands as infrequently as possible, perform the occasional apple cider rinse to lock in shine, and condition religiously [3] to keep your hair hydrated. But there's one styling sin that many rainbow beauties commit without even realizing: overusing your hot tools.

Hollywood colorist Guy Tang [4] took to his YouTube channel [5] to demonstrate the horrifying effects of heat styling on rainbow color. With the help of friend (and fellow stylist) Noora [6], he took a weft of purple-gray hair, then clamped it with a flat iron that had been heated to 400 degrees. In just five seconds, the beautiful hue had been faded to blond! Even when reducing the tool's contact on the strands to just one second, the color dramatically shifted. The duo went on to test this on permanent and demi-permanent dye, and the results were the same: significant damage to the color.

"[Clients] think if [the tool] is not at the highest level [of heat], it's not working and it's not doing anything to your hair," remarked Noora, "but it is — it's frying out your color." "Everything is vulnerable to fading," Tang added.

Curious as to why this happens? Noora explained it perfectly: "Like steam opens up the pores in your face, the heat opens up the cuticle in your hair shaft." The cuticle is the part of your strand that locks in color, so if it is lifted, dye can fade. That's why many stylists advise using cool water on color-treated hair.

If you can't live without blowouts or beachy waves, there are still some measures you can take. Tang recommended using lower heat settings and thermal protection sprays to keep your hue looking hot. But next time you're styling your hair, keep the pair's mantra in mind: "hot is good, but not for hair." Watch the mesmerizing video and prepare to be amazed!