I would like color my grout white to make it look new, but i am stumped at this "pre-cleaning" step?

Question

The grout is in my shower.

Is this cleaner good enough for the pre-cleaning, it is:

ZEP Commercial "Professional Strength"

Grout Cleaner & Whitener

on the label it says "Caution: THIS IS A VERY STRONG ACID PRODUCT"

Answer 1

Get you some good rubber gloves.  Never used the product so I can't say how good it is  (or isn't), but if you have that kind ov warning, get gloves.

Answer 2

Zep is a good product and should be more than adequate. Do wear gloves and open a window for ventilation.