Isotonix® products are water-soluble, they are very hydroscopic, and high heat and high moisture will cause the products to solidify in the bottle. Products that are left in the trunk of a car or in an enclosed vehicle for an extended period of time are exposed to high heat conditions. Keep the product in a cool, dry place, out of direct sunlight. The best storage conditions would be those with as little temperature fluctuation as possible. Isotonix® products contain only natural preservatives and anti-caking ingredients. Flow-Guard, a natural ingredient made from Silica, is added to ensure a free-flowing product. Also, Calcium Sulfate and Apple Pectin are more natural ingredients that are added to help the product remain free flowing. Finally, even though the products may be partially caked and lack eye appeal, the vitamin and mineral potency is not diminished.