Sir Ken is the one with the more eloquent answer on this, but the thing is, you dont see the damage straight away, or even on drying. The wool fibres will have been damaged to a certain extent by the high alkalinity, even if finished off with an acid or neutralising rinse. The amount of damage will obviously vary. This damage will in a reasonably short time will lead to a breaking down of the fibre and this may be noticable as wear on your next visit or the visit after. Our problem is, what do you do when faced with a filthy ingrained wool or wool mix carpet. Using woolsafe products on lightly soiled, well looked after carpets, is perhaps the ethical thing to do, but when faced with minger, we have to revert to stronger solutions, simply to get the desired appearance, allbeit at the cost of damaged wool fibre. Either that or it remains in an unnaceptable condition.
Dave