Quarry tiles are constructed of clay and provide a more coarse finish than most other ceramic tiles. Grout is usually placed between quarry tiles to help to hold the tiles together and to protect the tile from water and other damage. It is not uncommon for grout to dry on the face of quarry tiles during installation. Removing dried grout from quarry tiles can be a bit tricky, but is possible if you use the right products and methods.
Fill a bucket with warm water. Dip a sponge into the bucket of water, and wring it out lightly. Thoroughly wet the dried grout with the sponge and water. Moistening the grout will make it easier to remove.
Scrape away the grout from the tile using a wooden stick. You can purchase wooden sticks from most home improvement centres or make them yourself. Ideally, the stick should be oak and about 3/8 inch thick and 1 inch wide.
Use a broom to sweep away the chunks of grout that you were able to remove with the wooden sticks. Discard the grout.
Dip a rag in the bucket of water, and wring it out. Wipe down the face of the tiles with the rag to remove any more of the loosened grout. Rinse the rag frequently.
Moisten a nylon scouring pad in the bucket of water. Scrub the quarry tiles with the pad and water to remove the haze left on the tiles.
Wipe down the tiles with a damp rag. Follow up with a dry rag.
Apply sugar water to the tile if the grout residue persists. Dissolve 1 cup of sugar into a bucket with 1 gallon of warm water. Saturate several paper towels in the sugar water, and place them directly onto the affected tiles, leaving them for at least two hours. Remove the paper towels, and scrub the tile again with a wet nylon scouring pad. Wipe the tile clean with a rag and plain water. Buff the tile dry with a clean rag.
Use a commercial grout haze remover if grout residue persists. Such products can be purchased at most home improvement centres. Follow the manufacturer's specific instructions; application directions vary from product to product.