I have a newly tiled floor that has not yet been sealed. The grout has white blotchy discoloration over most of it. It seems to be superficial: it can be scraped off to reveal the original grout color below (but not rubbed off as with a towel). I have seen many recommendations for cleaning grout with vinegar, acetone, other acids, and other postings that indicate these substances will damage the grout. Can't I just lightly sand or scrape the grout before sealing?
Also, have decided that the *actual* grout color is still lighter than I had wanted anyway, and am looking into grout stain/sealer to change it. Will I need to remedy the white discoloration first or will the grout stain mask the uneven coloration?