Ok, that makes it easier to answer your question. Chemicall relaxers can have different straitening agents. First are the Sodium Hydroxise (lye) relaxers. Then you have the "no lye" relaxers. These would be the ones that use an alternative straigtening agent: Lithium, Potassium, Calcium hydroxide or Guanidine Carbonate. The degree of damage even though they are different chemicalls, is the same. It is just a way to fool the uninformed into thinking that the relaxer is less damaging because is a "no Lye" relaxer.
Then you have the Thioglycate ralaxers (or Thio). Thio is a milder chemicall which if applied correctly produces exellent results.
So how do you know whick kind to use?. Well the first ones mentioned above are for extremely course, kinky or nappy hair. These are the ingredients found on most african american hair relaxers. That's no to say that they can't be used on curly hair, however the degree of damage is a little more severe.
Thio relaxers are not designed for nappy or kinky hair. They have no effect on these types of hair. They are designed for curly or wavy hair. From my personal experience I have tried them both, and can tell you the difference is from morning to night. When I relaxed my hair with a regular relaxer (Sodium Hydroxide) I was able to make my hair straighter when I blowed dried. However I still had problems with frizz, and I just couldn't get the smoothness I was looking for. Plus it was really drying to my hair, ( and I had it professionally done). My hair is very curly and frizzie. And it turns into a big puff with the first sign of humidity. I Read about Rusk Radical Anticurl on a magazine once, and decided to give it a try. Rusk is a thio based relaxer. OMG, what a difference. My hair was totally straight, shiny and frizz free, in humidity, rainy days, or any other cruelty mother nature could throw my way. It was super soft and just plain amazing. And the most amazing thing was that if I wanted to wear my hair curly I could do that too. However the curl would be looser, smoother and frizz free. So I was hooked.
Now a warning about it. You must follow directions properly. The product should never touch your scalp. That is for any relaxer but specially for thio ones. That could cause bends in the hair and end up in breakage. It can also cause scalp irritation and damage to the hair bulb itself (again that is with any relaxer). I always recomend to have a professional do it. However you must make sure the professional is an expert on chemicalls, otherwise you might as well do it yourself, because all he/she is going to do, is follow the directions just as you would. Meaning you might end up with the same results. The advantage though to having it professionally done, is that it is easier for someone else to apply the product without touching your scalp, than it would be for you. Also you must use a wide tooth come to come the product through your hair. Make sure it is a good come (such as a mason pearson or a bone come). They don't have those ridges between the teeth, which most people don't know, are terribly damaging to your hair, specially when applying chemicalls. Those ridges rip away the scales that cover your hair strands, making hair very week, causing major breakage, and leaving it unable to hold on to color or deep conditioning or protein treatments. If your hair is wavy, Rusk or any thio relaxer (Redken Vertical, loreal x-tenso etc)would be the best choice for you, and will give you the best results. The only one I have been able to buy over the counter though is Rusk. If you can't find it at your local beauty supply, you can find it on Ebay. It costs about $17 dollars plus shipping. Also you can find it at Diamondbeauty.com. It comes in 3 different formulas #1 for regular non resistant hair. #2 for high lighted or high lift tinted hair. And #3 for course or resistant hair. One thing I found out through alot of reaseach is that even though the instructions say no to exceed 20 min, that is just a precausion by the manufacturer to avoid less experienced stylists overprocessing hair. The problem with that is, that other people end up with underprocessed hair. That is why you hear people complaining that they used Rusk and don't see much difference. For example my hair takes about 40 minutes to process. I didn't know that before, so even though I was getting good results, they werent as wonderfull as they are now. Your hair is wavy, so the 20 min rule should apply to you. Just use caution if you decide to do it yourself. Try to have someone else apply it for you if you don't know how to.
And last but not least, Sodium Hydroxide or it's comparable partners, are not compatible with Thio. So I you have any hair that has been relaxed with regular over the counter relaxers (the ones that cotain the chemicalls mentioned before) you can not relax that hair with Rusk because it will cause severe damage.
If you want a great hair regimen which will give you beautifull straight and frizz free hair, read my post on the straight talk forum, under "the fight against humidity". It works great, as the original poster can tell you.
Well I hope the information has been helpfull. I am sorry it took so long but I want you to make an educated decision, and avoid you a bad hair experience. I wish you good luck and beautifull hair.
P.S. For great information about this topic you can visit Verticalsinhair.com. It is great.