Where are the WECK jars produced?
The WECK jars have been produced in Germany since the company was founded in 1900. The WECK company glass works are in Bonn.
What are the WECK jars made of?
The WECK brand jars carry the technical term lime-natron-jars. These type of jars are made of about 70% quartz sand, 10% lime, 13% soda, low percentages of dolomite that makes the glass resistant to temperature changes, feldspar that makes it resistant and sodium sulfate that helps to prevent bubble formation. An important addition is recycled glass that nowadays quantitatively replaces the sand as the main component. Lime-natron-glass is the dominant mass produced glass and it makes up almost 90% of the glass production worldwide.
How does the preserving process work?
The micro-organisms contained in the food and air (fermentation germs, bacteria, spurs of mould etc.) are killed through heating and at the same time overpressure occurs. This presses hot air, steam and a bit of liquid outwards between the rubber seal and rim of the jar. Like a valve the overpressure and the rubber seal allow something to escape without letting anything into the jar. Thereby, a vacuum occurs after the jars cool down. This and normal air pressure ensure that the lid is sealed air-tight on the rubber seal and jar, even without the clips, which are removed after the preserving process.
How do you open the jar?
Simply pull the tab on the rubber seal. Air enters the jar with a hiss or plop. The vacuum is released and the lid can be lifted off easily. If there is no hiss or the lid can be moved without pulling on the tab, then the jar wasn’t sealed correctly. In this case the content is possibly foul and should not be consumed.
Why must the preserved food be taken out of the water bath directly after the end of the processing time?
The food will not be contaminated again but if the filled jars are left to cool in the the pot after the preserving process has finished, the total processing time will be extended. Consequently the content could become softer. Apart from that no adequate vacuum will be created and the jars won’t close correctly. Especially meat and meat based products could spoil if cooled slowly in the pot.
What is thermal shock?
The difference between the WECK jar (lime-natron-glass) temperature and the ambient temperature should not be more than 50°C. Otherwise it could come to a so-called thermal shock. If the temperature sinks or rises slowly, a WECK jar can withstand temperatures up to +200°. The jars can also be used for the freezer.
(Source: www.weck.de, as well as various WECK Landjournals)
