How to open a stuck jar lid in about ten seconds

There's a special kind of frustration reserved for a jar that simply will not open. The kids are waiting for brekkie, you're trying to slide a spoon into a jar of Vegemite for the morning toast, and the lid refuses to give. The good news is that a stubborn lid is usually a physics problem, not a strength problem, and most of the fixes take about as long as brewing a cuppa.

Over the years, Aussie home cooks have passed around a few trusty shortcuts that work in seconds rather than minutes. Some use nothing more than the kitchen tap and a bit of patience, while others rely on a humble rubber band or the blunt end of a wooden spoon. Below are the methods worth trying in order, from the gentlest to the slightly more forceful, so you can pick the one that suits the moment.

Why lids get stuck in the first place

Most jars use a metal lid pressed onto a glass rim during manufacturing. A vacuum forms inside the cooling contents and pulls the lid down, creating a seal. The same vacuum that keeps your food fresh is the thing that makes the lid a nightmare to twist off months later. Sugary, oily, or starchy contents can also creep up onto the threads of the lid and crystallise, acting like glue between metal and glass. A jar of Beerenberg jam from the Adelaide Hills, for example, is famous for its gorgeous sticky top, and famous for being almost impossible to open the morning after.

Temperature makes the problem worse. A jar kept in the back of the pantry will be cooler than the kitchen, so the metal lid has contracted slightly compared to the glass. That tiny difference in size is enough to lock the threads together. Once you understand that the lid is essentially stuck by physics, the fix becomes obvious: change one of those conditions in a hurry.

The hot tap water trick

The fastest method for most people is a quick run under the hot tap. Hold the jar upside down and let a stream of hot water play across the metal lid for about thirty seconds. Hot tap water in most Aussie homes sits around 55 to 65 degrees Celsius, which is plenty warm to make the metal expand. As the lid grows fractionally larger, the seal breaks and the lid usually twists off with a satisfying pop.

For a stuck jar lid that really refuses to move, pour water from a recently boiled kettle over a metal spoon and press the back of the spoon against the lid, repeating around the edge. The trick is to keep the heat on the metal, not the glass, since the glass is what needs to stay put. Dry the lid with a tea towel straight away so it doesn't slip in your hand, then twist. Most lids will give inside ten seconds once the metal has warmed through.

A rubber band for extra grip

Sometimes the issue is not the seal at all but the slipperiness of the lid. A wet, oily, or smooth metal top can be impossible to grip with bare hands, no matter how strong your wrists are. A thick rubber band wrapped twice around the lid gives the rubber something to bite into. Any wide elastic band will do, the kind that comes around bunches of broccoli or fresh herbs from the greengrocer.

A clean rubber dishwashing glove works just as well. Slip one on the hand that will be doing the twisting, and the textured palm grips the lid like it was designed for the job. A pack of heavy-duty cleaning gloves from Coles or Woolworths is a few dollars and will earn its keep on jam jars, pickle jars, and those oddly shaped pasta sauce bottles that never feel comfortable in the hand.

The upside-down tap

This is a classic for good reason. Turn the jar upside down, so the lid faces the floor, and give the flat edge of the lid a firm tap on a wooden benchtop or the heel of your palm. The idea is to push the lid slightly down into the jar, which breaks the vacuum seal. Once the seal is gone, the lid turns with very little effort. Many Aussie cooks swear by a single decisive tap, although a few lighter taps around the edge are safer if the jar is glass.

Avoid tapping the side of the jar, since that can crack the glass or chip a porcelain benchtop. Aim squarely for the centre of the lid face with the heel of the hand, or use the end of a wooden spoon. If the lid still won't budge after the tap, the rubber band trick or hot water method will usually finish the job. Together, the two methods resolve the vast majority of stubborn jars in the home kitchen.

The wooden spoon wedge

When a jar has been left in the cupboard for a year and the contents have seeped into every thread, sometimes the only way in is mechanical. Slide the handle of a wooden spoon or a sturdy butter knife under the rim of the lid and gently lever it up on one side. You should hear a soft hiss as trapped air rushes in. The hiss means the vacuum is gone, and the lid will now turn with a normal grip.

Be careful not to lever too hard or the lid can bend, which makes the next opening even harder. Slide, lever, hiss, then twist off by hand. Plastic jar openers shaped like a flat wedge do exactly the same job and can be picked up at Kmart, Big W, or the kitchen aisle at Bunnings for a few dollars. They are handy in a drawer and take up about as much space as a stack of coasters.

Purpose-built jar openers

For households that go through a lot of preserves, a proper jar opener is worth the small spend. The classic rubber disc, about the size of a biscuit, sits on the lid and grips it firmly when you twist. A good rubber model is dishwasher safe and lasts for years. Multi-handle grippers, the kind that clamp onto the lid and give you a long lever to turn, are popular gifts at Aussie kitchen shops because they work on every jar from small spice bottles to big pasta sauce jars.

While the kettle boils, those with a taste for a quick gaming break can usually fit in a round or two before the jar is ready to twist. Electric jar openers sit at the top of the range and take the wrist work out completely, although they are a luxury rather than a necessity. For most homes, a $10 rubber disc and a $15 gripper will cover every stubborn jar you ever open.

Stopping jars from getting stuck in the first place

A small habit at the back of the cupboard saves a lot of frustration later. When you first open a new jar, wipe the rim and the threads of the lid with a dry paper towel before you put the lid back on. Any sticky residue from jam, honey, or pasta sauce will harden over time and cement the lid in place. A clean rim also helps the rubber seal seat properly, which keeps the contents fresher for longer.

Do not overtighten the lid when you put it back. Most jars only need a gentle turn past the click of the seal. Forcing it down with all your might adds nothing to the freshness and makes the next opening a wrestling match. If you want to keep a half-finished jar of Vegemite or a stack of emptied Tim Tam jars in good nick for repurposing, store them with the lid just resting on top rather than screwed down. The glass will keep the contents safe for weeks at room temperature, and you will never again spend your Sunday arvo fighting a stubborn lid.

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