As a general rule of thumb, if there is a loss of sheen to the finish it is time for a recoat. There are two basic recoat methods: a screen and recoat and a chemical etching and recoat system. A screen and recoat involves lightly abrading the top surface of the finish with a screen or a pad and abrasive strip, then applying another finish coat. In a chemical etching and recoat system, such as the Tykote system, the existing surface is cleaned and chemically etched, then recoated. No sanding or screening is performed.
Work pictured is that of Timberline Hardwood Floors
The application of additional finish coats may need to be done every 3 to 5 years, depending on how heavily you live on your wood floor. See preventive maintenance for proper care instructions.
NOTE: If the floor has visible dents, scratches, wear patterns or cupping, recoating is not a viable solution, and it will be necessary to fully sand the floor to restore the finish.