Hi younggun...I haven`t used it before ...just ordered a bottle this morning so looking forward to trying it out...up to now, I`ve been darkening down my growing hair as it looks browner than the system hair [which is `1b`] ... I`ve been buying colouring products form a hairdresser supply shop but it`s a bit tedious and messy to do it..you have to squeeze this chemical from a tube, mix it with creme peroxide and apply to your hair...the longer it`s left on, the darker the colour...it also colours the skin if you allow it to lie on it...it`s also dangerous to eyes.... I imagine that prolonged use of such strong chemicals is not good for your growing hair... I like the idea of a product like `Back to natural` as I`m sure it`s not remotely as harsh. My guess is that it just `coats` both system and growing hair to the same colour... will do a post when I`ve received it and applied it. Paul.