 If an alkaline detergent is used on a woollen carpet, use of a mild acetic acid solution will  restore neutral fiber pH.
<meaning-changed>  If an alkaline detergent is used on a woollen carpet, use of a mild acetic acid solution will  restore neutral fiber pH.
 If an alkaline detergent is used on a woollen carpet, use of a mild acetic acid solution will neutralize the alkaline residues and restore neutral fiber pH.