For example, you want to be able to easily spray or roll paint on your wall without it clumping up. Researchers had to design paint so that it did not shear thicken. The same goes for cement, which needs to be poured at high speeds without seizing. On the other hand, shear thickening fluids can make body armor that hardens on impact, spreading the force across a larger part of the body, says Wagner. That protects soldiers, police, and EMTs from things like stab wounds or fragments flying through the air during an explosion.