When packaging, headspace should generally be kept as minimal as possible. However, when hot-filling products such as jams, it’s important to leave enough empty space between the contents and the Twist-Off cap.
You need about 8–10% empty space in the jar in order to create a vacuum during cooling. Too little headspace is counterproductive, as it prevents a reliable vacuum from forming.
Well-intentioned “overfilling” of the jar is therefore not recommended.
If you have any product-specific questions, feel free to contact our packaging experts at any time.
