It’s an interesting story. Since the dawn of sailing, mariners were aware that wet sails were more effective at capturing the wind than dry ones. One problem: Wet cloth is also heavier, and the added weight negated any speed advantage that wetness might’ve provided. It wasn’t until the 15th century that Scottish sailors began applying grease and fish oil to heavy sailcloth to repel moisture—but that stuff was pretty nasty. In the mid-19th century the Royal Navy was using linseed-oiled flax for its sails and by the turn of the 20th century, lightweight paraffin-waxed Egyptian cotton sails had completely transformed commercial shipping.