Keratin treatments for straight, smooth hair has reached major popularity among our readers. According to Eric Rosado, Artistic Director at Ted Gibson Salon in New York City, keratin treatments are truly, "the best option for defrizzing and smoothing many textures of hair from curly to relaxed."

Mauricio Ribeiro, creator of the Brazilian Blowout, says that since their launch, keratin treatments have evolved so much — and customers no longer complain about a strong chemical smell. That said, the process won't work without chemicals.

"To get shiny, straight hair for months, formaldehyde or other aldehydes must be used," explains Chemist Doug Schoon, president of School Scientific in Dana Point, California. "I believe [clients] have no risk" of being harmed by the treatments, he added.

Bottom line, the choice is yours when it comes to deciding if a Brazilian keratin hair treatment is right for you. To make your decision easier, read on to get answers to commonly asked questions about keratin and feedback from readers on some of the big-name treatments.

There are so many keratin hair treatments available now, so if we missed one that you love or one that you had a bad experience with, please tell us about it by commenting on this story.

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Also known as Brazilian hair treatments, keratin hair treatments are a semi-permanent, hair-smoothing, curl-softening professional chemical treatment. They make hair straighter, shinier and even healthier. The treatments are usually made up of a chemical like formaldehyde (which creates the long-lasting smoothing effect), conditioners, and some keratin (a protein our hair is made of to add strength).

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The Japanese hair straightening treatment (a.k.a. thermal reconditioning) is permanent — it actually changes the internal structure of your hair, removes all curl to create pin-straight strands and may damage hair. It's also not very popular anymore. "Japanese doesn't fight frizz or cut blow dry time in half," says Rosado. "It just straightens your hair."

Comparatively, keratin treatments only last three to six months (depending on the product used and your lifestyle). They will not straighten — only soften — curl (though they will straighten waves). However, they do eliminate frizz and can make hair healthier over time.

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Typically your hair is washed with a clarifying shampoo and blow-dried before the treatment is applied section by section, and combed through the hair. Then, you may sit for a bit with the keratin treatment on your hair before the stylist blow-dries your hair a second time, and seals the treatment onto your strands using a flat iron.

Next, one of two things will happen — you'll either be done and walk out the door knowing you can't wash your hair, put it in a ponytail, get it wet or put it behind your ears for 72 hours, or the treatment is rinsed out, hair is blow-dried and you leave knowing you don't have to wait any time to style or wash it.

The entire process takes two to four hours depending on your hair type and length. (There isn't really a difference in results between these two styles, just that newer technology is allowing users to wash and style their hair sooner after treatment.)

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If you spend a ton of time blow-drying and flat-ironing your hair and/or have curls that you want to loosen, or if your hair has frizz or lacks shine, you're likely a good candidate.

Keratin hair treatments work on a variety of hair textures including African American hair types, and color-treated or previously chemically-treated types, according to Jordana Lorraine, stylist and keratin hair treatment technician at the Dino Clark Salon in Santa Monica, California.

Do avoid Brazilian keratin treatments if you are pregnant, have severely damaged hair from too much bleaching, bleached hair that's superfine, stick-straight hair or have slight waves you want to keep intact. Basically, if your hair can stand a 450-degree flat iron, it can handle this treatment.

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