When the food and jars are heated to more than 80 degrees C, all bacteria that occur naturally on food are going to be destroyed. At the same time, through the heat, the food and air inside the jars will expand and some air will be pushed out of the jar. 

When the jars are cooled down, the pasteurised food and air inside the jar will contract again, what creates a vacuum inside and this will hold the lid on the jar. You can remove the clamps now, these are not needed anymore. 

Your food now is safe to be stored. If the lid still is fixed on the jar, your food should be safe to eat. If the lid is only sitting lose on the jar, some bacteria inside might have been active and produced some gas. Please don’t consume this food in that case.

If you want to preserve food by heating and pasteurising (see above) or if you want to seal and close the jar, then you will need to order rubber rings and clamps. Without clamps, the lid will sit loose on top of the jar.

With every jar type we have indicated what size of rubber rings are needed for these specific jars. There is only one size of clamps, so you don’t need to worry about clamp sizes. 

All jars come with lids included, so there’s no need to order additional lids.

With Weck jars you can combine food preservation (or fermentation) with design. The jars are made for pressure to be released from the jar during the preservation process or during fermentation, but no air will get back inside the jar when sealed with rubber rings and clamps.

Put the rubber ring in between the jar and the lid and put the lid on top. Or alternatively, put the rubber ring on the lid and put both on top of the jar. 

Then take 2 clamps, put it on the edge of the lid and press them down along the sind of the jar until properly closed (one after the other). Your jar is properly sealed now.

To open again, just pull the little tongue of the rubber ring until you hear the air flowing into the jar and take off the lid. Simple, right?

That is really difficult to say. If you properly sealed the jars and then heated up to over 80 degrees C for at least 10 to 20 minutes (depending on the size of the jar – all food inside needs to be above 80 degrees), then all bacteria inside are destroyed. Your food will be ok to be stored for a long time. 

After opening, bacteria will have made their way inside of the jar, so you will need to put it into the fridge and consumer quickly.

However, if the lid is sitting lose on top of the jar after preservation, some bacteria seem still to be active inside. In this case, it would be advised not to consume the food. 

Yes of course. Weck jars are designed to release pressure out of the jar (for example when heated during preservation). The same applies when you ferment food and bacteria or yeast produces some CO2 and other gases. 

Weck jars are a great way to ferment your food: not only because they are perfectly suitable, but also as they are available in all different forms and sizes – and they look great, too.

Jars with screw caps might be very convenient to use. However, during preservation and fermentation, there will be additional pressure inside the jar that will need to be released. If you close your lid of the screw cap jar tightly, no pressure can be released (that is dangerous, when too much pressure builds up, your jar might even explode). If you don’t close it tightly, it won’t seal the jar and bacteria and yeast from outside can get into the jar. For these reasons, jars with rubber rings and clamps (such as Weck or Kilner) are a safe way for food preservation and fermentation. They seal the jar and avoid bacteria and yeast from outside to get in, but the can release pressure out of the jar during the preservation process or during fermentation. as possible for your customers.