How to keep curly hair straight, after you straightened it?

i have really curly hair, and it straightens out well when i use a CHI but how do i keep it straight in humidity? what products should i use?How to keep curly hair straight, after you straightened it?
I put a lil John Frieda Frizz blocking serum when my hair was wet yesterday and let it air dry. When it was dry, I used the Bed Head Control Freak serum on my hair before and after I straightened it and my hair is still straight. Even though I put a little of John Frieda on my hair when it was wet, it is definitely the Bed Head Serum that is making my hair straight now. Oh yeah, just a little advice, use JF serum on wet hair and BH on dry hair, it's easier that way...I thinkHow to keep curly hair straight, after you straightened it?
You can go to a salon and have it 'relaxed' which is like a perm but instead of making it curly they make it straight - bye bye straightner
i have the exact same problem and would love to know a cure to this! i've tried loads of products and stuff but they never seem to work :(
a new flat iron... this may be expensive but look at metropolis technology.