Thinset mortar is a reliable and easy way to attach tiles to floors, walls and counters, as long as you mix it to the right consistency and allow proper drying time after setting the tiles. The humidity, temperature and air flow in a room affect how long it takes to dry, but thinset generally is cured and ready to walk on or grout in 24 to 48 hours. Some installers and home specialists recommend waiting 72 hours for tiles applied to floors. Visible mortar on the sides is not an accurate indicator for when the tile is set because the portion in the center is not receiving air and therefore is drying more slowly.
Follow manufacturer directions for mixing to the proper consistency, because the thickness of the mortar at application determines how long it takes to cure. Avoid spreading too much thinset on the surface so that the tile does not slip and dry unevenly. General guidelines include mixing to the consistency of mayonnaise and using a notched trowel for application. The proper size notched trowel is determined by the type of tile; follow manufacturer recommendations.