For many women (including, reportedly, Meghan Markle), the secret to smooth, shiny hair sits at the end of a keratin treatment. The de-frizzing process is more popular than ever, but can you afford it? What does it actually do, and how long will it last? There’s a lot of mystery surrounding keratin treatments, so the Cut created a handy guide to explain it all.

So, what is a keratin treatment?

A keratin treatment is a chemical process that smooths and shines frizzy hair. Results can last up to six months. There are many different versions of the treatment that go by different names (Brazilian Blowout, Cezanne, Goldwell Kerasilk) and your hairstylist can customize a blend of the formula to suit your needs. Some versions of the treatment release formaldehyde when heated (more on that later), but many newer versions, like Manhattan hairstylist Arsen Gurgov’s proprietary “Rio” keratin treatment, are formaldehyde-free. No matter the formaldehyde content, on a basic level, keratin treatments dive into the hair follicle and inject porous areas with keratin, an essential hair protein. Your hair will appear healthier because it actually is.

Can you walk me through the process?

“The length of time it takes to do a keratin treatment depends on the formula the stylist is using, as well as your hair texture, and how much hair you have,” explains Gurgov. Expect your salon visit to last anywhere from two to four hours. When you arrive, your hairstylist will first wash your hair. Then, the hairstylist will either apply the keratin treatment to your wet hair and let the formula saturate each strand for about half an hour, or the hairstylist will blow-dry your hair first and then apply the treatment — again, it all depends on your hairstylist and your hair needs. “Finally, I go over any coarse strands with a flat iron on low to medium heat depending on where the treatment needs to be sealed in,” Gurgov says, and then you’re done!

Okay, is it different from a chemical relaxer?

Absolutely. While keratin treatments are temporary and wash out after a few months, straightening chemical relaxers are permanent. The two treatments also use different ingredients that produce different results. Using a main ingredient of sodium hydroxide, lithium hydroxide, potassium hydroxide, or guanidine hydroxide, chemical relaxers break and restructure the bonds in curly hair so that the hair becomes weaker and straighter. Instead of altering the chemical composition of your hair, keratin treatments inject the porous parts of your hair with protein, so that it feels smoother. After a few months, this washes out. Some treatments may contain a solution that releases formaldehyde when exposed to heat (there are also many new formaldehyde-free options).

Can I do this at home?

Technically, yes, but don’t expect salon results. You’ll first need to buy the right products. Many treatments contain the word “keratin,” but that doesn’t automatically make them “keratin treatments.” All hair is made up of “keratin proteins,” so keratin-named products aren’t rare. To get the best experience at home, look at the product’s ingredient list. A lot of smoothing treatments are intense silicone and conditioning treatments. After that, look at the instructions. Do they provide extensive instructions on how to wash, dry, and straighten your hair? If not, you probably have a standard conditioning product and not a keratin treatment. And even if you buy an actual keratin treatment, your results won’t last as long as the salon version. Where a salon treatment can last for several months, at-home versions tend to wash out after a few weeks.