In the late 1960s, women looking for an answer to the question of how to get straight hair found it in the iron, which they'd use to get pin-straight locks. That's right, not a flat iron—an iron iron. As in, on an ironing board. The kind typically used for clothes.

Mercifully, hair-straightening technology has come a long way since then. But no matter the decade, the grass is always greener on the other side: just as many straight-haired beauties pine for bouncy ringlets, so too do some of the wavy- and curly-coifed still long for sleek strands of their own.

Below, we've compared three of today's most popular techniques for achieving straight hair, taking an investigative eye to what makes them ideal—or not—for different candidates. And we'll make sure to direct you to a hair salon, not the laundry room.

Three Types of Hair Straightening

1. Flat Ironing

How it works: You grip a small lock of hair between the iron's heated plates, then move it down the lock so the heat can reshape the hair.

How to keep hair straight after straightening: Avoid water and humidity!

The cool part: There are many types of flat irons, and the technology is always advancing, so you can outfit your bathroom vanity with everything from ceramic plates to bright pink handles to built-in timers that turn the iron off when it's not in use. Plus, many flat irons can be used as curling irons, too—check out some YouTube tutorials if you're unfamiliar with this technique.

Pro tip: Depending on the brand, those with tighter curls might not get the stick-straight results they desire.

2. Keratin Hair Straightening

How it works: Different chemical products steep hair in keratin, filling in gaps on the shaft and coating the strand in smoothing layers of formula that a stylist then sets with heat.

How to keep hair straight after straightening: Avoid water in the first 72 hours and switch to keratin-friendly shampoos and conditioners.

Wach a video showing the process and the results with two of our beauty experts.

The cool part: It's customizable. If you just want to soften, but not straighten, your texture, your stylist can help you use a gentler formula.

Pro tip: If you have wavy or straight locks, you should anticipate replacing frizz with gloss. Some stylists also like to use keratin before administering a short chop, like a pixie.

3. Thermal Reconditioning

How it works: Chemical products break the curl structure of the hair, which is then rinsed, blown dry, and flat-ironed before the stylist applies a neutralizer.

How to keep hair straight after straightening: Avoid damaging hair ties and shampoos (look for products specially formulated for reconditioned hair), and make sure to schedule touchups as new growth appears or if some waves reappear (a possibility with certain hair types).

The cool part: Did we mention it essentially lasts as long as the treated hair does?

Pro tip: Mention all past treatments to your stylist, even if it's something that seems gentle, like henna. Also avoid putting hair in a ponytail during the first 72 hours or you risk permanently denting it.

Take a closer look at the differences between each method with the table below:

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