Who said make it neutral? You can not make it neutral if you do not know what it is, so I think you have read the post wrong.
Stain removal is a skill, but a very simple one to learn, but you wil always be learning. Do a stain and spot course, you will learn so much, it will really make a difference to your cc skills.
PH scale 1 -14. acid is one, alkaline is 14. all stains fall in this 1-14 ph scale, except solvent type stains, tar,oil etc. lesson one over, easy wasn't it.
next teacher