Taking Care of Straightened HairQ: Once the hair is straightened, how do you take care of your hair? i.e. What products do you use? Do you continue to use a blow dryer or does your hair dry naturally? Can you go to a spa and use their steam room like a day or two after this process is done? What can or can't I do?
A: Well, what you can and can't do with newly straightened hair depends entirely on what kind of straightening process you've had.
If you're just referring to having your hair blown dry and flat ironed to be straight, then your hair is going to revert back to its normal wave pattern as soon as it is exposed to moisture and/or heat. However, I presume you are referring to a more permanent straightening process.
In this case, there are two possibilities. The first is that you have had a thio or hydroxide straightening process. These straightening processes are "permanent" in that the hair will stay mostly straight, but may need some extra smoothing (such as with a flat iron) to look perfectly flat after shampooing and drying. You can blow dry the hair if desired, or leave it to dry naturally. With both of these methods, you want to make sure to condition your hair every day - even if you don't shampoo it. These techniques tend to leave the hair a little more porous and therefore they need extra moisturizing and protection when being blown dry or heat styled.
You should also know that if you have had a thio straightening process, you can simply re-perm the hair to restore curl when and if you desire. With hydroxide straightening, the chemical side bonds of the hair have been permanently broken and the hair cannot be repermed to restore the curl (in fact, to do so will destroy the hair). You can, however, use curling irons, hot rollers and wet roller sets to give the hair temporary curl. (You can also do this with thio straightened hair.)
For the thio and hydroxide straightened hair, a gentle, moisture-rich shampoo and rich, moisturizing conditioner are important to help keep the hair moisturized. Spending time in a steam room will present no hazards, but you may find that your hair gets a little frizzy in the high heat and humidity of that environment.
If you are referring to the Japanese Hair Straightening, or Thermal Reconstruction, you can literally do anything you want and not worry about your hair staying straight. You can blow dry it, and will probably find that the hair dries faster than before because there is less penetration by moisture into the hair shaft. For the thermal reconstructed hair, use the shampoo and conditioner products recommended by the stylist who performed your process.
Visiting a steam room presents no problems in this case either, and you shouldn't even see any physical change in the hair from the heat or humidity. According to the creators of the process, you can restyle the hair with temporary curls as desired, or even perm the hair after the process (but given the high cost of the process, this would seem to be a strange thing to do).
The rest is common sense. Be cautious with heat styling, and avoid things that might damage the hair, even if it were untreated.
Permanent hair straightening
What is Thermal Restructuring?
Heat styling basics