This stress will be tensile during temperature decrease, or compressive. during temperature increase. If the compressive stress level exceeds the column buckling resistance of. the restrained length, then lateral buckling (or snaking) will occur.
Dry Time. In most cases, you should allow the grout to dry overnight before using that room as total dry time may take up to 24 hours. If you are thinking about sealing your grout after you have installed it, you need to wait even longer than that so that all of the moisture has had time to be released.
After about 15 minutes of set time use a damp sponge to wipe tiles clean of excess grout, regularly rinsing sponge out in bucket of clean cool water. I do each area twice before I move on to more grouting and will use more than one sponge through the process of the whole room.