The two strips of silicone atop Bio Ionic’s flat iron plates seem silly, but they serve an important purpose. By buffering the outer edge of the plates, they reduce your chances of hair snags. They also force you to glide the flat iron more slowly through your hair (they are called speed strips, after all). While the slower technique maximizes shininess and smoothness, the speed strips can become a bit of an obstacle if your hair is thick.

Both inexpensive and high-end flat irons come with a wide range of features. If you plan to travel out of the country often, then a tool with dual voltage might be a good option. Or you might find that the Bio Ionic’s vibrating plates are something you can’t live without after trying. A long cord that swivels at the end of the handle to ensure ease of use might also be an important feature for you. Some features you might not need include pads to rest your flat iron or gloves to protect your hands — both accessories our testers didn’t think were necessary. When researching flat irons, make a list of your must-haves and make sure the one you choose includes your top features before purchasing.
Seemingly small details like cord length can make all the difference in the effectiveness of a beauty tool. A longer cord length is desirable here, giving you more freedom and versatility depending on the power outlet situation in your home or your hotel if you're traveling. A cord with 360 swivel capabilities is also a plus. You'll be moving your hair straightener all around your head as you style, and a rotating cord will keep it from getting tangled.
Titanium is a lightweight metal that heats up very quickly and can hold high heat at a consistent temperature. This material is ideal for those who have thick, curly, or natural hair that can be more difficult to straighten. Since it's lighter than ceramic, it also makes for a lighter hair straightener overall, which means less arm strain as you're taming your mane. As someone who has very thick hair, I can attest — Any feature that can make styling easier and faster is a plus.
Though it looks high tech with an LCD screen, this budget-friendly straightener has impressed Amazon reviewers everywhere. "I have very thick curly/wavy hair and in a matter of 45 minutes my hair was the straightest I’ve ever been able to get it by doing my hair on my own," wrote one reviewer from Florida, who said her straight hair managed to endure the state's humid climate.
It comes with the most advanced heating element in this industry. Using a digital display, you can adjust temperature from 280F to 450F. This means that you can use it to style fine or very fragile hair as well as very thick and coarse. This is the model that is often recommended for women that have hair that is hard to straighten and difficult to keep straight. So if lower heats do not work for you, use the highest setting, and get pin straight results, like glass.
This feature is particularly beneficial for users with naturally wavy or curly hair, which can have a tendency to easily snag in hair styling tools. This floating design, combined with the heat sensor, also ensures that your gorgeous curls won’t become permanently damaged just because you decide to straighten things out a bit for an evening or two. After all, those curls are coveted by beauty pros the world over, and you never want to damage them just because of a styling trend!
There are 25 heat settings (200 °f-450 °f) that are digitally controlled. It heats up to 450 degrees almost in an instant, making it a perfect solution for maintaining keratin treatments. You can use it without the infrared lights and still get great results, but when you turn them on, you will not believe the change in your hair quality, that will be visible immediately.
“Being a mom of two, it’s hard to have time to get my hair done, but with this, I do my hair in 30 minutes, rather than over an hour. I haven’t bought a new straightener in probably four years, and I bought this with very little expectations. OMG! First of all, not only did it take half the time to do my hair, but it left my hair as amazing as I always wanted it! Super silky-smooth. I then used it to make some curls on my 8-year-old. In less than 15 minutes, I was done with her hair and she was in love with the curls.”

Curling irons, also known as curling tongs, create waves or curls in hair using a variety of different methods. There are many different types of modern curling irons, which can vary by diameter, material, and shape of barrel and the type of handle. The barrel's diameter can be anywhere from .5 in (1.3 cm) to 2 in (5.1 cm). Smaller barrels typically create spiral curls or ringlets, and larger barrels are used to give shape and volume to a hairstyle.

Despite these downsides, the HSI Professional comes with plenty of positives, including extras not often found with other hair straighteners. Along with the straightener, you'll receive a carrying case, a heat-resistant glove for easier hair styling, a style guide, and a travel-size argan oil leave-in hair treatment serum to smooth and protect your hair. This is more than most high-end hair straighteners come with, all for a fraction of the price.


“I’ve owned a Conair, Chi, and I-Tech straighter before, but this one is FABULOUS! There really is no tugging at all on your hair — so smooth, and I was shocked that it truly heats up in 15 seconds, as advertised! It also does something magical to my hair: It adds more shine like no flat iron has done before. Mind you, my hair is very difficult to deal with. It has always been coarse, wavy, dry, and thick! This iron worked beautifully on my hair.”

Ceramic and electrical straighteners were introduced later, allowing adjustment of heat settings and straightener size. A ceramic hair straightener brush was patented in 2013.[6] Sharon Rabi released the first straightening brush in 2015 under the DAFNI brand name. The ceramic straightening brush has a larger surface area than a traditional flat iron.
The two strips of silicone atop Bio Ionic’s flat iron plates seem silly, but they serve an important purpose. By buffering the outer edge of the plates, they reduce your chances of hair snags. They also force you to glide the flat iron more slowly through your hair (they are called speed strips, after all). While the slower technique maximizes shininess and smoothness, the speed strips can become a bit of an obstacle if your hair is thick.
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