3. Sulfamic Acid Cleaner
I mixed the sulfamic acid (buy it here for $4.48) cleaner with warm water, according to the directions on the container. I spooned it out onto the grout, and it immediately began to fizz and bubble up. This is clearly strong stuff. Right away, I scrubbed at it with a Scotch-Brite pad and the grout looked darker. I panicked a little but rationalized that it must have been because it was still wet. Whatever the scientific reason was, it did eventually become lighter and cleaner-looking than the original grout. I rinsed the area thoroughly.
Here are the results of the three methods. The grout in front of the lemon slice is the area that I cleaned with lemon juice, the middle one is Oxiclean, and the one on the right is sulfamic acid cleaner.
The verdict: they all worked to some extent, but Oxiclean worked the best. Lemon juice was a very close second, and would be a great option if you’re trying to stay organic.
I decided to go with the Oxiclean method for the rest of the bathroom. The only frustrating part was the white residue that appeared after everything was dry… so I went over it with the mop again and now it looks great:
Quite a difference! See the whole bathroom below. As I noted before, our grout is a gray color so it will never look bright white – but it is certainly less stained and grimy than before. I hope this was helpful, good luck cleaning your dirty grout! Feel free to share other methods that you’ve tried in the comments section below.