Episode 4: Tartaric Acid Crystals | Japanese Wine

This poster of grapevines catching hold of an American fighter plane is an interesting use of propaganda to help galvanize public support for the war effort. The poster encourages farmers to grow great quantities of grapes. Crystalline potassium sodium tartrate from tartaric acid, a byproduct of winemaking, was used as an integral material for sonar detection systems deployed to hunt US submarines during World War Two. The sonar systems used the Piezoelectric Effect where crystals display a visible electrical reaction generated via sound waves. These days we think of these crystals as wine diamonds or wine stars, but they were viewed as essential to conducting the war in the Pacific in the early 1940s. The propagandists clearly thought a picture of a fighter plane would be more of a motivator to land-locked farmers than a picture of a submarine.