Those with passionate views about how much to tip the pizza-delivery guy, please see the information in the footnote provided by two other sources. (For a look at the real reasons we tip and whether tipping has anything to do with the quality of service we receive, click here.)
Liquid Grout Sealer. 1  1. Allow new grout to cure for 48 to 72 hours before sealing. 2  2. Tape off baseboards and other nearby surfaces to prevent unintentional staining. 3  3. Apply sealer using a foam paint brush, paint pad or a small roller.  4. Wait 5 to 15 minutes to allow the first coat to soak into the grout.
In most cases, however, it is not the slate that will stain, but the grout between individual tiles. How you clean that grout depends on whether it is colored or non-colored. A sealer can keep floors cleaner. For colored grout, always test cleaners in an inconspicuous area before using them on the stain.n most cases, however, it is not the slate that will stain, but the grout between individual tiles. How you clean that grout depends on whether it is colored or non-colored. A sealer can keep floors cleaner. For colored grout, always test cleaners in an inconspicuous area before using them on the stain.