In home canning, food is packed into the jar, leaving some empty "head space" between the level of food and the top of the jar, then the lid is placed on top of the jar with the integral rubber seal resting on the rim.
Food is packed into the jar. This was in home canning. Food was leaving some empty "head space" between the level of food. This was in home canning. Food was leaving some empty "head space" between the top of the jar. This was in home canning. The lid is placed on top of the jar with the integral rubber seal resting on the rim. This was in home canning.