DEEP CLEANING: Think of deep cleaning your wood floors in the same way that you think about shampooing your carpet. You use a vacuum cleaner to pick up loose dirt and debris but the vacuum doesn't have the ability to chemically treat stubborn stains. The same goes for wood floors. The deep cleaning process uses chemicals which are not safe for everyday use and really should be used by a trained technician. The deep cleaning product I use is IFT by Basic Coatings (See the Amazon link below). When used properly, IFT will gently and effectively break down stubborn buildup that regular cleaning leaves behind. This stronger solution has the muscle to penetrate through oily residue, some waxes, soap residue, food stains, and other nasty stuff WITHOUT damaging the top layer of finish on most varieties of wood floors. Paste wax finished floors and Danish Oil finished floors are not suitable for IFT. Be sure to read the directions carefully before using any product such as IFT and test in a small inconspicuous area for potential problems before using on the entire floor. After IFT is used to clean up the muck, you'll see on the towel or in the autoscrubbing machine just how dirty your floors were. The final step in the deep cleaning is a rinse to remove any remaining IFT and rinse away any broken up crud left behind from your previous passes. This step is critical and you don't want to leave IFT on the floor without rinsing it with Squeaky (See Amazon link below). If the top protective layer of finish on your floors is in stable condition, the original sheen should return to the floors. Clarity should be restored and the floors should feel clean to the touch.