How the WECK® method works.

...and what goes on inside the jar during processing

The WECK canning method which has proven its reliability over the past nine decades is based on two simple principles which act together. They are based on laws of nature and can neither be altered nor improved.

First Principle:

The natural, normal spoilage of fruit is caused by microorganisms (e.g. yeast, bacteria, mold, spores, etc.) which are present in large numbers in foods as well as in the air. During processing, all these microorganisms living in the food being canned and in the air trapped in the jar are killed. The jar is sealed off from the surrounding air by means of the lid, rubber ring and spring clamps.

Second Principle:

During the heating process, pressure higher than normal is created in the jar. As a consequence, hot air, steam and sometimes even small amounts of liquid are forced out of the jar between the rubber ring and the jar rim. The lid and rubber rings which are fixed on the jar by means of the spring action of the clamps act similarly to a one-way valve, i.e., they allow air, steam and sometimes even some liquid to escape from the interior of the jar, but do not allow air and cooking water to enter the jar from the outside. As the jar is cooling down after processing , a vacuum is created inside. The normal pressure of the air surrounding the jar presses the lid down onto the jar rim and onto glass; this pressure causes a firm and permanent seal of the jar.


1. Jar ready for processing

Lid and rubber ring applied and clamped on with two spring clamps.

2. Jar during processing

The jar contents expand due to heating. Pressure is created within the jar. The spring clamps allow air, steam and sometimes even some liquid to escape from the jar, but not to enter it.

3. Jar after cooling down

A vacuum now prevails in the jar. The normal pressure of the surrounding air outside the jar presses the lid down on the jar, thus firmly sealing it. The spring clamps required during the canning process are now unnecessary and should definitely be removed after the jars have cooled down.
The processed, cooled-down jar remains sealed exclusively by means of the normal air pressure exerted on the jar lid. No additional mechanical device or force is required. If you want to open a jar: Simply pull on the tab of the rubber canning ring away from the jar until you hear a "ps-s-st"; this sound indicates that air has entered the jar, thereby destroying the vacuum which was created by processing, and releasing the lid from the jar. The lid and rubber ring can now be easily removed.