How can I clean Spanish tile that has dulled out and has stains?

Cleaning Spanish tile is easy. Just fill a bucket with a gallon of warm water and add 2 tablespoons of liquid dish soap. Dip a mop in the solution and then ring out excess water. Wipe the mop across the floor using long even strokes. Dip a cleaning brush into soapy water and scrub heavily soiled areas. Repeat until all soil has been removed. Mop the floor once more to get any loose dirt up. Let the tile air dry.

Use a soft rope mop or soft sponge head mop with warm water to clean when the floor starts to look dull or grimy. Do not use a metal mop head, which could potentially scratch and harm the terracotta tiles.

There are professional cleaning products on the market that are designed specifically for cleaning terracotta tiles. These products are usually available at home improvement and flooring stores. Or ask your tile installer what he recommends when cleaning the terracotta tiles.

If you prefer the natural way to clean, try equal parts of white vinegar to a bucket of warm water and then mop the tiles accordingly. Vinegar is good for removing any oily materials or debris on the tiles and dries quickly.

If you have other stains such as water, you might want to try using some Linwood oil, also available at home improvement and flooring stores. Use a small amount on a slightly damp mop head after you are done washing the floor. Spread a light coat the oil evenly on the tiles moving from wall to wall. Then, let the floor dry for at least 24 hours before walking on it or replacing furniture. Move all furniture and other accessories that might get ruined or covered in oil prior to using.

Be sure to avoid harsh chemicals on the terracotta tiles; they could become permanently discolored or damaged if the wrong cleaning products are used. If you're in doubt, don’t use.

https://www.youtube.com/watch?v=EuWkOWpOSlY

Where do I get Linwood oil?