Caress,
here's one thread on clarifying. If you type "clarify" as a search word and search ALL POSTS in the hair discussion forum, you should find many more threads on the same topic.
I have heard of people adding baking soda to their shampoo to make a clarifying shampoo. I did it once and for the time the shampoo was in my hair, I smelled a scent reminiscent of days when I relaxed my hair. (You know, that smell after the chemicals have been applied and are doing their work.) I'm natural so that scared the pants off me and I rinsed it off in a hurry. Whether I used too much baking soda and just about stripped my hair starkers, I don't know; but I think the next time I decide to clarify, I will use a shampoo meant for that.
Someone once shared that she never clarifies because she uses ACV rinses at the end of her wash. So do I, and have been doing it since my baking soda incident. And so I guess I'll won't be reaching for a clarifying shampoo any time soon either. I won't hesitate to use one though if my hair stops responding to the products. I'll use that as a cue, since it'll say to me that I have too much build-up preventing products from reaching where they're needed. So far, I think I'm doing fine...but that might be because it's less than six weeks since I "clarified"...