Storage & Containers

Mason Jar

Sealed glass jar for preserves, pickles, and storage

A threaded glass jar with a two-piece lid for canning preserves and pickles, storing dry goods, and packing overnight oats or layered salads. The airtight seal keeps things fresh, and the clear glass shows what's inside. Sterilize jars and lids before canning.

A mason jar is a threaded glass jar sealed by a two-piece lid — a flat metal disc with a rubber-gummed edge, held down by a screw band — and it's one of the most genuinely useful objects a kitchen can stockpile. The design dates to the mid-1800s and was built for one job: home canning, where the flat lid forms a vacuum seal as a hot jar cools, preserving jam, pickles, tomatoes, and chutney shelf-stable for a year. But the same airtight, see-through, oven-and-freezer-tolerant glass has made it the default vessel for a dozen everyday tasks too.

Stack them and the kitchen runs more smoothly: dry goods stay fresh and visible, overnight oats and layered salads pack neatly, vinaigrettes shake and store in one jar, stocks and soups freeze in portions, and a cleaned jar becomes a drinking glass or a vase. They're cheap, near-indestructible, infinitely reusable, and standardized — lids and bands from one brand fit jars from another. Just respect glass's two weaknesses: it doesn't like thermal shock, and it doesn't like being filled to the brim before freezing.

Types & varieties

Regular mouth

Narrower opening that's better for liquids and pouring, and slightly cheaper. Less ideal for reaching in with a spoon or packing whole fruit.

Wide mouth

Wider opening for easy filling, spooning, and packing — the right choice for overnight oats, salads, and freezing (the straight or flared shoulder resists cracking as contents expand).

Half-pint / pint / quart

Half-pint for jams and single portions; pint for dressings, dry spices, and salads; quart for stock, big-batch pickles, and bulk dry goods.

Smooth-sided (no shoulder)

Straight-walled jars expand safely when liquids freeze — the safest choice for freezer storage; shouldered jars trap expanding ice and can crack.

European Kilner / Le Parfait style

Clamp-and-gasket or swing-top jars that seal with a rubber ring and a wire bail — reusable for pickling and dry storage, though processed differently from American-style two-piece canning.

Canning safely

Home canning is forgiving only if you follow the rules, because a bad seal can grow dangerous bacteria. Use a fresh flat lid every time (the gummed seal is single-use), sterilize jars and lids, and match the method to the food.

Always use new flat lids — bands and jars are reusable, the sealing discs are not
Water-bath canning is for high-acid foods only: jams, pickles, most tomatoes, fruit
Low-acid foods (vegetables, meat, beans) require a pressure canner, not a water bath
Leave the specified headspace and listen for the lid 'ping' as the cooling jar seals

Freezing without cracking

Glass and freezing liquid are an uneasy pair: liquid expands as it freezes and a full, shouldered jar will crack. Choose the right jar and leave room.

Use straight-sided, wide-mouth jars made for freezing
Leave at least 2–3 cm of headspace below the shoulder for expansion
Cool food fully and freeze with the lid off, then tighten once frozen solid
Thaw in the fridge, not by plunging a frozen jar into hot water

Common uses

Canning jams, jellies, pickles, chutneys, and tomatoesAirtight storage for dry goods — flour, grains, beans, spices, coffeeOvernight oats, chia puddings, and grab-and-go breakfastsLayered mason-jar salads that stay crisp for daysShaking and storing vinaigrettes and dressings in one vesselFreezing portioned stock, soup, and sauceQuick refrigerator pickles and fermentsDoubling as drinking glasses, vases, or organizers

Tips & pitfalls

Avoid thermal shock — don't pour boiling liquid into a cold jar or take a hot jar straight onto a cold counter; warm the jar first.
Tighten canning bands 'fingertip tight,' not as hard as you can; air needs to escape during processing to form the vacuum.
A sealed canning jar's lid stays flat and won't flex when pressed — if it pops back, it didn't seal, so refrigerate and eat it soon.
Build a salad in a jar dressing-first, then sturdy veg, grains, and greens on top; it stays crisp until you shake and pour.
Standardized lids and bands cross brands — buy spare flat lids by the box so you're never short during canning season.
Soak a stubborn label in warm soapy water; the residue lifts with a little oil and baking soda, leaving the jar good as new.