Let's start with what's NOT gluten free:
KMS California-
I haven't been able to verify this, but the owner of the hair salon I go to says independent laboratory testing has shown that any claims you find on their website about being gluten free are FALSE. I haven't been able to find any research on this, but I'm not taking chances.
Unite-
I sent them an inquiry a long time ago, and got a massively enthusiastic response:
I want to reassure you that our entire line is gluten free, even though you may see the word "wheat" in our products such as the "wheat protein", it is simply the chemical name, but the wheat has already been stripped out. Our products go through a hydrolysation process, in which the wheat is stripped out and all that is left is the protein. I am 100% positivve and knowledgeable about our line and therefore can assure you that it is 100% wheat free!! I hope this helped, please let me know if you have any other concerns.
I was wary of that response and therefore didn't buy any of the products. Turns out, that was for the best. As I read in this post by the Gluten Free Makeup Gal, the TTB doesn't consider even stripped wheat protein to be safe enough for beer to be labeled gluten free. Why should I allow it in my hair care, if they won't allow it in beer?
Chi-
I had seen on the Gluten Free Cosmetics List that some Chi products were gluten free, and seen elsewhere (though I now can't remember where) that some of their products were GF. My face, however, says otherwise. Perhaps I simply picked up the wrong items. So, either check carefully or avoid Chi.
As for what is safe, that seems to be the question of the hour. I only have a few companies that I trust as of now.
ShiKai-
Most of their products are gluten free. (See this post for exactly which ones are and are not).Onesta-
They still have two products that are not gluten free (not sure which ones--sorry!) but they are working on fixing that! By summer, their entire line should be safe.
For others, be sure to check out Gluten Free Makeup Gal's list of safe products. She has a few hair care companies on there. Also check out the Gluten Free Cosmetics List. It's about $20 for a lifetime membership. I'm not sure how often it's updated, however.
I'll try to update this list as I become aware of more!
What gluten free hair care products do you use?