These were originally coated with Cetol. Belt sander 80 grit, then 150 grit. Finally quick buff with 200 random orbital sander and they feel like glass. First few years I used Penofin oil. It was too expensive. I now just wipe them down with a coat of Watco Danish Oil (Fruitwood color) each spring. It doesn't build up and takes 5 minutes on your way off the boat to put on a coat. Only need to do the outsides from time to time. Insides only got done the first time.