Quite simply: to make the food last longer. In summer, fruit and vegetables are cheaper or maybe you grow them in your own garden. By preserving them, we can also enjoy them in the colder months. Plus, preserving is fun!

The micro-organisms contained in the produce and the air (fermentation germs, bacteria, mould spores, etc.) are killed by heating. At the same time, the heat creates excess pressure. This pushes hot air, steam and some liquid out between the rubber ring and the rim of the jar. It is like a valve: thanks to the excess pressure and the rubber ring, some air can escape, but nothing can enter the jar. This creates a negative pressure – a vacuum – in the jar as it cools after preserving. This and the normal pressure of the outside air ensure that the lid then sits permanently tight on the ring and jar – even without the preserving clips, which you have to remove after preserving.

Simply pull on the tab of the preserving ring. Outside air will then enter the jar with a hiss or pop. The vacuum is released and the lid can be lifted off easily. If no hissing is heard or the lid can be moved without pulling the tab ("touch test"), the jar was not sealed correctly. In this case, the contents may be spoiled and should not be consumed.

In general, we do not give any best-before dates, because nothing at home is standardised as it is in industry settings. We don't know the freshness and quality of the ingredients, the hygiene, the adherence to temperatures and times. Even the age of the spices used can play a role in shelf life! And the fattier the contents of the jar, the shorter the shelf life. This applies to meat as well as pre-made meals, but also to cakes. As you can see, it's not that easy to guarantee a certain shelf life of a preserve.

As a rough guide, however, on the assumption that you've done everything right, the quality is good, the jars, rings and clips are used properly and fully functional, and the preserving cooker works faultlessly, then the following applies for fruit and vegetables: from harvest to harvest (i.e. about 1 year), for meat and ready meals: from slaughter to slaughter (about half a year) for cakes and bread: about half a year.

Once you've opened a jar, you should store it in the fridge. The WECK keep-fresh lids are super practical. They're made of food-safe plastic, are easy to put on and take off again and protect the food from germs and bad odours.

There's nothing wrong with that, but:

- Preserved food usually keeps longer than frozen food.

- You can use preserved food immediately – frozen food has to be defrosted and prepared first.

- Space in the freezer is limited. A large freezer costs electricity and money all year round.

All that are cylindrical or conical: tapered jars, cylinder jars, gourmet jars, quadro jars. With these shapes, if a layer of ice forms during freezing, it can expand towards the mouth of the jar. Jars that curve outwards in the middle can crack as a result of this.

Yes, but you should allow them to defrost briefly, otherwise they may tear when you peel them off. Alternatively, you can also freeze your jars with a rubber ring, jar lid and clips.

As the contents have to be turned upside down here, the tapered jars are best. But the quadro jars are also great for use with baked goods.

30 minutes at 100 °C.

The problem is the batter. To ensure that bread and cakes slide out of the preserving jars easily after baking, the jars must be greased and sprinkled with flour beforehand. When baking sponge cakes, the baking tins must not be greased, as the batter needs to stick to the tin in order to “climb” up the sides. If the tins are greased and sprinkled with flour or breadcrumbs, it cannot do this and therefore does not reach its usual volume. If you put the batter in ungreased jars, you will have a light sponge mixture, but you will not be able to remove it from the jar easily after baking. So you can bake sponge cakes in jars and preserve them, but cakes made from a more traditional, fat-rich batter, shortcrust pastry and yeast dough are more suitable for baking in jars.

Primarily, of course, for preserving and juicing (if you use the juicer). However, it can also be used to heat up large quantities of food and drinks and keep them warm. This is particularly useful for large parties.

Simply wash the pot with or without a tap thoroughly with washing-up liquid and warm water and then rinse the tap with clean water.

The filled and sealed preserving jars can be placed directly on the bottom of the pressure cooker – however, it is advisable to place a sieve insert or cloth underneath them. Pour 500 ml of water into the pressure cooker. Close the pressure cooker according to the instructions and switch on the hob. The preserving time begins when the pressure cooker valve reaches the level (ring) listed below.

Soft berries (e.g. raspberries): Level Ⅰ (ring); 5 min preserving time

Other berries: Level Ⅰ (ring); 7-8 min preserving time

Jams, marmalades & jellies: Level Ⅰ (ring); 1-2 min preserving time

Pome and stone fruit: Level Ⅰ (ring); 10-12 min preserving time

Pickled vegetables: Level Ⅰ (ring); 10 min preserving time

Vegetables: Level Ⅱ (ring); 25-30 min preserving time

Meat and sausage products: Level Ⅱ (ring); 25-30 min preserving time

Pre-made meals: Level II (ring); 30 min preserving time

Cakes and bread: Level I (ring); 10-12 min preserving time

You can find more detailed information in our WECK Preserving Book.

Place the filled and sealed preserving jars on the wire shelf in the steamer. The jars should not touch each other or the side walls. Fill the water tank with water. A heating element heats the water, which is then fed into the cooking chamber as steam and surrounds the jars on all sides. A temperature of 100°C should be maintained in the cooking chamber.

Fruit and vegetables, sweet and sour: 60 min; vegetables (briefly blanched beforehand): 150 min

After the preserving time, carefully open the steamer, remove the jars and leave to cool on a cloth folded several times.

You can find more detailed information in our WECK Preserving Book.

WECK preserving jars are technically known as soda-lime glass jars. Our jars are made from approximately 70% quartz sand, 10% lime, 13% soda, small amounts of dolomite, which makes the glass less sensitive to temperature fluctuations, feldspar, which makes it more resistant, and sodium sulphate, which prevents bubbles from forming.
Another crucial ingredient is also added: recycled glass, which now even replaces sand as the main component in terms of quantity. Lime-soda glass is the predominant type of container glass, accounting for almost 90% of the glass produced worldwide.

Natural rubber that doesn't deform even at -40 degrees.

Don't use any binding agents such as flour or sauce thickeners. Over time, these can make preserves taste sour and unpleasant. Therefore, only add binding agents when opening or reheating. The same applies to milk or cream. Dairy products are not suitable for preserving and should therefore only be added before serving.

Unfortunately, rice, pasta or other carbohydrates can't be preserved either. The contents of the jar would ferment and spoil within a short time.

If you're making jam, marmalade or jelly, take a teaspoon of the fruit mixture after the specified cooking time and place it on a porcelain plate. If you swirl it, the mixture may "move", but it should start to become gelatinous and set quite quickly. The fruit mixture is then ready and can be filled into the jars.

You can reduce the sugar or even leave it out completely if you're preserving fruit or fruit puree. You can also use xylitol or erythritol. Honey can also be used, but important nutrients are lost during the preserving process due to the heat.

We do not recommend this, as many baby foods contain carbohydrates, which can affect their shelf life.

With various ingredients, you would have to turn the heat up to about 2 hours, which would destroy the valuable nutrients in the baby food. It's better to freeze baby food.

Yes, for example, if you want to add lentils or tofu to your Bolognese sauce instead of minced meat, preserve the sauce for 90 minutes at 100° C afterwards.

Our test kitchen hasn't managed to achieve any presentable results for this yet.

We advise against this. Fruit, vegetables and, above all, meat should only be preserved from fresh. This is the only way to minimise the build-up of bacteria and other germs.

By lowering the pH value of the contents of the jar by adding a little vinegar, which inhibits bacterial growth. Another option is preserving a pressure cooker. As the bacteria are very resistant to boiling, higher temperatures can also be achieved through higher pressure.

This is probably caused by "flat sour" bacteria, which make food acidic. These bacteria occur more frequently in vegetables that are close to the ground and rich in protein, especially those grown in a wet year. Excessive fertilisation can also play a role. The bacteria form acids, but no gases, so the jars usually do not pop open, but the contents taste sour.

In the more than 100-year history of WECK, we are not aware of any case of botulism in connection with preserving jars made according to the WECK principle. Please always follow the instructions/guidelines in recipes, including those in the WECK Preserving Book. If you use high-quality ingredients and adhere to the times and temperatures, then you can eat your preserves with gusto! Preserving twice at 24-hour intervals used to be done in the past, when the refrigeration options for food were not as optimal as they are today. If you're still unsure, we recommend preserving in a pressure cooker. Due to the higher pressure, they reach almost 120 °C and can therefore reduce the preserving time to 30 minutes.

Yes, because with the "old" WECK fluted or solid-rim jars, this was an indication that the jar was tightly sealed. With the new round-rim jars, however, the flap points clearly downwards. If you arrange these jars strategically on your storage shelf, you can easily monitor their closure by visual inspection.

No, unfortunately spare parts are no longer produced for our old jars.