Jars for Preserving: Where to Get Them and Reusing Old Ones

Old jars are fine to use again for jam, chutney and pickles as long as the glass is sound. The lid is the part to replace: fit a new one every time you fill a jar. That makes a good store of empty jars nearly free, and the only regular cost is lids.

Where to get jars for little or nothing

Empty jars turn up in most households, so you rarely need to buy many. A few places to look:

Jars from other people arrive with unknown histories. Treat every one as a candidate, not a keeper, until it has passed the checks below.

Which old jars are fine to reuse

Soak off any labels in warm soapy water first, then look at each jar against the light and run a finger round the rim. The top edge is where the lid seals, so a nick there matters more than a scuff on the side.

Scratches deserve more attention than they look like they need. Metal knives and spoons used to scrape out a jar over months leave fine etching on the inside, and glass weakened this way can crack when it meets boiling water or a hot filling. Thin shop jars that once held things like mayonnaise can be used for acid preserves such as jam, chutney and pickles, but expect more of them to break or fail to seal than proper preserving jars. Keep those for your least precious batch.

Once a jar passes, wash it and store it dry with the lid off until preserving day. Every jar still needs sterilising before it is filled, and it must be completely dry when the preserve goes in. Use the oven, the dishwasher's hot cycle or hot water, as set out in the sterilising guide. Check the jar maker's instructions first; some (Kilner, for example) advise against the oven for their jars.

Lids: when to replace them

Lids go on straight away while the preserve is still hot, and a vacuum seal forms as the jar cools. (How to tell a lid has sealed, and what to do with one that hasn't, is covered in jam and chutney from a glut.) A lid is made to seal once, so a used one can't be trusted to seal again.

Replacement lids are sold on their own by cookware shops and preserving suppliers. Neck sizes vary, so measure across the top of the jar, or take one with you, to be sure the new lid matches. Check new lids before use too: one that is dented, bent or out of shape should not go on a jar.

Twist-off lids and vinegar

Vinegar and other acids attack bare metal. Lids made for preserving have a coating on the inside for that reason. When acid does reach the metal, it leaves a dark deposit on the underside of the lid. The deposit on its own is harmless. Over a long storage, though, acid can eat pinholes through the lid, and if the pitting goes right through, the jar is no longer sealed and the contents should be thrown out.

For chutney and pickles, that means:

• choose lids with a coating on the inside, and don't use a new lid whose coating is already scratched
• don't lift lids out of hot water with a metal tool, as it can scratch the coating and give the acid a way in
• leave only the small gap under the lid that a tested recipe gives: too little and the preserve presses on the lid, too much and the trapped air can darken chutney
• don't use any lid that shows rust, and store filled jars somewhere cool and dry so lids stay sound

Clip-top jars with rubber seals

Clip-top jars have a glass lid, a wire clip and a separate rubber seal. The glass and clip can be used again and again. The seal is sterilised on its own by simmering it, not in the oven with the jars. The rubber seal does the job a twist-off lid does, so the safest course is the same rule: a new seal each time you fill the jar. Never use one that is split, hard, stretched or won't sit flat. Check the jar maker's instructions for its seals.

Which size of jar suits which preserve

Choose the jar size by how fast the household will get through a jar once it is open, rather than by how much you made. Opened jam and chutney belong in the fridge and are best used within a few weeks to a month or two, sooner for low-sugar jam. A big jar that sits half-eaten for months is more likely to end up in the bin. (For opened and unopened times in full, see how long preserves keep.)

Keep jars of one size together for each batch if you can. Matching jars fill evenly, take the same lids and stack neatly on the shelf.

If you are making a big batch from a glut, count your jars before the fruit is picked, using the yield your tested recipe gives.

Common questions

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