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Are mason jars really airtight

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If you've ever heard a rumour that Mason jars are airtight, you're not alone. In fact, the idea has been circulating for years. But is this really true? I've had lots of questions about Mason jars, how they work and what they can be used for: everything from storing food to making candles and even repurposing them as drinking glasses. Let's explore whether or not it makes sense to call these glass jars airtight!

Mason jars are sometimes marketed as being airtight. But does this actually mean they don't let any air in or out?

The short answer? No.

The long answer is that, while mason jars can be made to be airtight, they're not meant to be and don't hold up well under the pressure of being sealed tightly for long periods of time.

They're much better suited for keeping things fresh than for preserving food by reducing oxygen levels (which preserves shelf-life). In fact, because they aren't completely airtight they're often recommended by people who want to preserve their own jams and pickles at home! And if you fill up a jar and press down on the lid and it stays put, then it's airtight...

Air really is not compressible, so if you fill up a jar and press down on the lid and it stays put, then it's airtight.

If you want to know if your mason jar is airtight, put it on a scale and weigh it. If the weight of the jar doesn't change, then it's airtight. In other words, if you fill up a mason jar with water and press down firmly on its lid until there is no discernable gap between the top of the metal lid and the rim of where it meets glass on either side, then your mason jar should be sealed tightly enough that no oxygen can get in or out—and thus no changes in weight will occur as long as there aren't any leaks anywhere else (like cracks in other parts).

The reason for this is simple: Air isn't compressible; therefore, when you press down on anything containing air (such as an inflated balloon) only one thing happens—the amount of space inside gets smaller and smaller until there's no more room left over for anything else to fit inside! That means all those molecules start pressing against each other closer together; which has two effects: 1) that thing now weighs less than before because less empty space exists between all those atoms being compressed by greater force onto one another; 2) since there are fewer empty spaces between them now compared to before being pressed down onto one another harder than normal...then obviously these molecules have nowhere left within their new boundaries left over anymore either!

Mason jars were originally intended to be used for canning food--preserving it in an airtight container.

The jar was designed to have a rubber seal around its rim, which created an airtight seal when the lid was applied. As you might expect, this design made them the perfect vessel for storing foods that needed preserving.

The humble mason jar has since taken on new roles beyond their original intention of preserving food, however. In addition to being used as drinking glasses and flower vases, they're also commonly found today as storage containers or even candle holders.

It's clear that these humble vessels are versatile enough to find use across all kinds of applications!

When food goes bad, it's because the bacteria that causes decomposition gets into it.

Let's take a look at what happens with your food when you use Mason jars.

The good news is that these little guys are airtight! The bad news is that they aren't watertight or even airpressure tight (if you put them under water, they will leak). So there will be some oxygen getting in there which means these jars won't keep your food fresh for long—but this depends on how much oxygen has gotten into them by opening them too often or not storing them properly with lids screwed on tightly enough to seal out all the air inside.

The inside of the Mason jar lid has a rubber seal that makes the jar airtight when you heat-process the jar during canning and then place the lid on top.

This rubber seal is called a gasket. The gasket is made of rubber, which makes it soft and pliable so that it can fit snugly into place after being heated. This creates an airtight seal between your jars and lids during heat processing (canning).

When you buy Mason jars, some come with these lids already attached; other jars require purchasing separately. If you're buying new jars for canning purposes, just make sure that there's an option for purchasing both lids and rings separately before making your purchase!

The Mason jar is still popular today! It's used for everything from drinking glasses to flower vases to storage containers.

It's also a classic style that will never go out of fashion.

A Mason jar with its lid secured tightly is an extremely good way to store almost anything.

You can use Mason jars to store just about anything from food and cosmetics to small pets. They’re lightweight, they look great on a shelf, and they’re very inexpensive. Plus, they come in a variety of sizes with matching lids so you can organize your life as much as you want.

Mason jars are airtight meaning that even if you don't have the lid secured tightly (e.g., your hands are full), it won't open on its own until pressure inside the jar builds up due to outside temperature changes or movement of its surroundings (e.g., wiggling while putting it away). However, there are still ways for mason jars not staying airtight even when properly sealed by using different materials or methods than those recommended by manufacturers."

So, does that mean Mason jars are airtight? The answer is yes! They are airtight when you heat-process them during canning and then place the lid on top. However, if you don't heat-process them before storing food in them then they won't be airtight at all.

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