Unglazed ceramic tile and grout have a matte finish that's extremely popular. However, due to the rougher finish, these decorative items tend to attract and hold dirt more firmly than their glazed counterparts. It is not particularly difficult to clean unglazed ceramic tile and grout, but it takes more time.
Mix your cleaning solution. In the 5 gallon bucket, combine 1 cup of vinegar, 1 tsp. of dish detergent and 1 gallon of water. Slosh it around to mix the solution, or use a rag to stir it together. This mixture will not hurt your hands, but it will make them smell strongly of vinegar, so wear rubber gloves.
Scrub the dry tile hard with a stiff scrub brush. This will remove a fair amount of dirt, dust and debris. Using a stiff brush will not hurt unglazed tile and grout; any new scratches or rough spots will not show on the grout, and the tile should not scratch.
Moisten a rag with the vinegar solution and wipe down the tile. The vinegar will remove any mold and mildew stains while cleaning the tile in an environmentally-safe fashion. Each time the cloth begins to dry out or get dark with stains, rinse it thoroughly and begin again.
Rinse the entire area with clear water and a clean rag. If you have serious mold or mildew, consider skipping this step; letting the vinegar solution sit on the grout and tile will help kill any remaining spores. Otherwise, use a rag that has been moistened with clear, clean water to wipe down the entire area. This will cut the vinegar smell and leave your tiles fresh and sparkling.