Yes, cork requires sealing followed by resealing every few years. The sealant helps protect cork floors from moisture, stains, and scratches. Most homeowners use water-based polyurethane, which costs about $10per quart.  You can also use acrylic or carnauba wax to seal and create a protective layer, but you need to strip and reapply these two options more frequently, about every six months to one year.