Acid is a chemical!
I'm new, but I have read this entire thread, and I am concerned. Rio & Copa used acids to straighten hair also, and were very damaging and drying.
Unlike almost all other parts of our body, our hair is "dead". Once it grows from the root, it is essentially a protein shaft, with NO living cells, and NO blood flow. When it is cut, we do not feel it. Only if it is pulled from the root. There is NO real way to "repair" our hair. Once damaged, that is it. Once the bonds are broken, or "loosened", that's all. Please research this, if it sounds difficult to believe. Check the web. All of the products, and conditioners out there are leading us on, all are temporary fixes. You can out a patch or band-aid on it, but it will not, and cannot "heal" like organs or skin. Simple biology.
Products can make the hair "feel" better, softer, smoother clarified, etc. But damage cannot be undone. It can be covered over, or "filled in" temporarily, but never permanantly. The cuticle opens and closes with heat (or chemicals ...lactic acid for example), but once split, its never made whole. Vitamins do their work at root level, below the skin. Past the scalp, what's done is done.
Some peoples' hair is stronger and more elastic than others, so they can use more chemicals without "apparent" damage. The cuticle layer can take more abuse on naturally straight hair, than the thinner-cuticled curly hair, before it finally breaks or splits.
All this is to say, be objective. Natural chemicals can be just as damaging as synthetic ones. If you have "natural" hair, with no relaxer, and you have been putting this lactic acid bath on your hair to "loosen" it, this is a natural, "gradual" (three times a week?) relaxer! Lactic acid does the straightening. Those who use lye/no lye relaxers are rolling the dice too. There is no way to regulate how acidic this lime or lemon versus that lime is, or how acidic this batch will be. Damaged hair can also be incredibly "soft", and "manageable".
It takes years to grow hair. It is precious. Be careful.