I have yet to straighten my hair because I am still learning new ways to complete the process with minimum heat damage. This happens when the hair strands are broken down and extreme amounts of heat are used. This permanently straightens the hair.
To help minimize damage, it is always best to use a heat protectant. That way, once the straightened hair is washed, it will revert back to it's curly state.
Lots of women who are natural decided to straighten their hair every now and then to achieve a new look. I am all for this! I think that this is one of the best things about being natural is its versatility.
Now what's the difference from heat damaged hair and heat trained hair? Let's take a look.
Heat Damaged Hair:
Look going for: A straight and sleek look temporarily
The results: Hair that has been under extreme temperatures and will not revert back to it's curly state, it will continue to stay straight or a looser curl pattern will appear even when washed
Heat Trained Hair:
Look going for: A straight look that will be permanent
The results: Hair continues to stay straight at does not curl back up even when washed
Q: Some people ask.. "Are you still natural if this happens"?
A: Yes, your hair is still natural, but it's proteins have been broken down. So in a sense, both cause damage to your hair.
The point is, some people would like to be natural and continue to wear their hair in straight and sleek styles. If their desire is to wear their hair straight most of the time, these people will probably call their hair "heat trained." While others may only want to achieve this style a few times a year and if their hair does not revert back to curls they may call this "heat damage." It really depends on what the person's goal is.
If I ever straightened my hair and after a wash, it didn't revert back to curls, I would be upset and call this "heat damage" because I want the best of both worlds. Both curly and straight. I can't achieve that if my hair will not curl back up.
Things to remember:
Proteins break at 311 degrees F
Hair loses water at 122-248 degrees F
Hair burns at 451 degrees F
Here is a good example that should help with understanding. Always do what works for you!