Understanding Canning Lids

Understanding Canning Lids

One of the most important factors to consider when preserving food is the jars themselves, and specifically the canning lids you use to keep them sealed shut. The entire purpose of this style of cooking and preserving food is to keep the oxygen from getting in, so the lids you choose and how you use them is extremely important.

For beginners to food preservation, it can seem like there’s a lot to learn, but understanding canning lids is quite simple. There are a few different types you need to be aware of and also have some basic knowledge about what to do when something goes wrong.

Canning lids.

With this quick guide, you’ll get all of the information you need about canning jar lids and how to use them the right way.

What Makes Canning Lids Seal?

The canning lid sealing is what keeps the food product inside preserved, but what exactly makes them seal? This is all thanks to a rubber ring found inside the lid which creates a seal when it’s placed on. These two individual parts, the lid, and the ring, can be separated and you’re able to use a ring more than once, whereas the lid should only be used once.

Once the food is placed inside the jar, you then screw on the lid with a ring which traps all of the air inside. The gases that come from the food and air can actually expand when they’re heated which is why it’s essential to have the ring tightened around the lid otherwise it could potentially explode.

One of the most amazing things that occurs when canning food is the ‘pop’ sound that can be heard during the process. This is due to the heat then coming down again once you’ve finished boiling the foods inside, normally when they’re resting on the kitchen counter.

This drop in temperature causes the air pressure within the jar to decrease which means the lid is being sucked down into the jar. The vacuum it created helps to pull the lid down which makes the popping sound go off, which is a good sign for someone in the preserving process.

This vacuum would keep going but the trusty lid is in the way to prevent it from moving any further.

The Types Of Canning Lids

There are two types of canning lids to choose from when preserving food, and each has their own benefits. The first is a metal coated lid which is usually recommended as it’s the only USDA recommended lid. They’re also BPA free and are known to create the tightest seal for this type of use, however, you need to buy from a trusted brand in order to verify its quality.

Canning lids.

Plastic canning jar lids are also common but generally not as popular at the metal variety. The bonus to these is that they’re a reusable and resealable canning lid so you can get more value for money.

However, depending on where they’re made and what company you buy from, there is the risk that they might not seal as well due to the rubber gasket. This means it won’t vent as well and there is an increased chance it won’t stay sealed as long.

What Happens If The Canning Jar Lids Fail?

One of the worst things to happen in the food preservation process is the lid failing, and sometimes it’s not obvious what the cause is. When a lid doesn’t work properly it will let oxygen into the food and not have it pressurized correctly which can be dangerous in the process and also for the food that’s been preserved.

Canning food is a traditional preservation method and therefore some people rely on outdated information when getting started. The National Center For Home Food Preservation is an up to date and official place where you can get the most recent guidelines on canning food, but you can also try these tips if the lids seem to be failing.

  • Don’t use any jars or lids that were not made specifically for canning.
  • Check the rims of the jar and the lids for any chips or cracks that might impact how well they are sealing.
  • If liquid leaks out of the jar during the sealing stage then you’ll need to remove some of it and clean off the edge of the jar so that it can seal correctly.
  • The food might not have been packed correctly without sufficient air removed from the food that’s being preserved, which can leave residual air in the jar.
  • The screw bands on the jar need to be checked for rust or marks as this can prevent them from sealing correctly.
  • Lids must be prepared according to manufacturer’s guidelines before putting them on the jar, as each brand might require something different.
  • Measure the headspace of the jar before screwing the lid on always.

An Important Part Of The Food Storage Process

People often worry too much about the jars themselves or even the type of processing method they’ll use, but finding quality rings and lids is just as important. Without a steady lid on your jar won’t be able to trap oxygen inside or hold the right amount of pressure, and all of your food product inside would go to waste.

Canned lids that say "Canned with love".

Choosing the right lids and rings for your jars is essential, and though it might be tempting to opt for something cheaper to purchase it simply won’t hold up as well in the long run. When you’re preserving food for the purpose of having it around for years to come, the canning lids are one of the most important investments you’ll make.



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