We recommend wiping out containers with paper towels and a little rubbing alcohol to remove any dust or debris that might be left from the packaging. This helps ensure that your wick stickers will adhere completely to the container. Also, to reduce flaws such as frosting, air bubbles, and wet spots, you can heat the jars before pouring the wax. Use a heat gun, heat lamp, or place the containers in a warm oven (about 100 degrees) for a few minutes before pouring your wax.