Black spots on wood can also appear due to prolonged exposure of water and metal nails forming the iron oxide.
Black spots on engineered hardwood.
For more on black spots see my previous article what causes mysterious black spots in wood floors.
Unlike white water stains residing on the very surface of the hardwood floor dark stains require more steps and products in order to restore the beauty of the wood.
The gulf coast area home was late 1970s construction with a concrete slab.
With the proper care hardwood floors will last a lifetime.
It reacts with the tannin in the wood and turns black.
Black rings or dark water marks can be more problematic as these are generally water stains that have penetrated into the finish of the floor.
These discolorations will cause your hardwood floors to look old and dingy.
Dark spots on hardwood flooring are commonly the result of some type of liquid that has soaked into the polyurethane finish and top layers of wood.
Over several weeks and even months the mysterious crud spread onto adjoining floors and materials.
However items such as oil water grease and pet urine will create black spots on the hardwood floors.
Last january i was commissioned by a flooring manufacturer to inspect a prefinished 3 inch engineered oak floor that had developed dark spots.
Dip a small brush such as a toothbrush into a small amount of bleach and rub onto the stain.
I considered black iron oxide contamination but such spots encapsulate once the finish is dry and do not spread.
Ceramic tile sheet.