Like Mark (@mmayo) I use teak oil on darker woods and on blonde woods just wipe on poly. I use about 6 coats, let it sit for 24 hours, between coats and use 00 steel wool between each coat and then finish it off with either buffing on my Beale system or Renaissance wax. Biggest problem I have is people love to let them soak in water. Instruct whoever to make sure just to clean the blade only and apply a quality wax to the wood routinely. I've never had a knife returned. Hope this helps.