The heat protectant spray helps you protect your hair. When you straighten, curl or blow dry your hair it damages it. Especially when you blow dry with a brush, you need to hold your brush away from your blow dryer because the metal tips on your brush are being directly heated by the metal on your brush and that BREAKS YOUR HAIR!! This is how you get split ends. So when your blow drying your hair always remember that when you brush your hair while your doing this, dont hold your hair dryer directly ontop of your brush, keep them seperated.
The heat protectant spray helps minimalize everyday damage to your hair. Your should NEVER add heat to your hair without heat protectant spray EVER! Split ends are the number one thing that has killed my hair.
Also, My hair adjusts with the heat outside. When its a really hot day my hair wiill go instantly curly, especialy right around my face, my bangs get really curly. When you are ready for the day and your hair is perfect, you go out and then your hair starts to curl around your face and your like "Well I looked good 30 minutes ago" ... well you dont have to say that anymore, because with heat protectant spray it stops the annoying curls you dont want. Or if your hair is the opposite of mine and it goes straight when you want it curly because of the heat, that will happen less often if you use heat protectant spray.
You dont need a lot of it. You apply it to the top of your hair and all the way to your ends. I always make sure I flip my hair upside down and I spray it underneath. DONT USE A LOT, because your hair will get greasy. You just want to apply enough that you cant feel that your hair is wet, this is very important. if you apply too much the spray will act like hair spray and make your hair greasy.
And just because I sware by treseme doesnt mean you have to do. If you have a brand you stick to, look for it in your brand. I love treseme because its something that has always worked in my hair no questions asked. I have tried many products and tresme is the only kind that doesnt leave a greasy feel in my hair.