1. Fill the jar approximately 1 inch (2 cm) below the edge.

  2. Turn over the glass lid, so that the writing and WECK strawberry are facing upwards.

  3. Turn over the glass lid again and place it with the rubber ring onto the jar.
  4. Seal the lid using 2 clamps.
  5. During the preserving, the topmost jar (or the highest one) has to be fully covered with water. The rubber ring prevents the incoming of any water during preserving.
  6. After preserving - and when the product has turned cold - it is time to remove the clamps. If the jar is closed tightly, the preserving was successful and the content is safe to eat.


The normal and natural spoilage of fruits, vegetables and meat is caused by micro-organisms which are circling through the air. During preserving, the micro-organisms are killed inside the jar.

Through the heating process an over-pressure is created within the jar. The glass lid, rubber ring and clamps act as an over-pressure valve; letting go of air, steam and eventually liquids from the inside of the jars, whilst simultaneously protecting the inside of the jar from the outside air and boiling water.

During the cooling process, a vacuum arises inside the jar. The clamps are now redundant and have to be removed - giving you the opportunity to check if the jars are closed. With the passing of time, carbon dioxide pushes open the glass lid if the product within spoils. This is a significant sign of spoiled food, and saves you from eating your preserves without being sure.