Preserving Jars

Clip-top jars are faster to fill and close and the gasket is replaceable, which suits a kitchen doing short runs often. Screw-band jars use a separate flat lid, which gives a very reliable seal but the lids are usually single-use.

Decide by how often you run. Frequent small batches favour clip-tops; big seasonal runs favour screw-bands.

By testing it rather than looking at it. A properly sealed jar holds a vacuum, so the lid will not flex and the clip or band will be under tension, and a jar that fails will usually fail within the first day.

Follow a tested preserving method from a reliable source for the specific product rather than a general rule. We do not publish processing times or temperatures against jars.

Yes, and it is the thing most often neglected. Rubber hardens and takes a permanent set, and a flattened gasket will look fine and seal badly.

Keep a stock of spares and replace them as a batch rather than one at a time. Check whether spares are listed on the product page specifications before standardising on a jar.

They work well for anything you want visible and sealed in small quantity — spices, dried fruit, infusions, bar garnishes. Glass does not stain or hold smells the way plastic does.

For bulk dry goods the weight and breakability count against them. See kitchen storage boxes and ingredient bins.

Washed thoroughly and handled so the rim stays clean, because the rim is the sealing surface and a chip or a smear there is what causes a failed seal.

Sterilising requirements come from the preserving method you are following for that product, not from the jar. A commercial dishwasher handles the washing stage.

In a production area, yes. On a line or anywhere near a service pass, glass is a risk that is hard to justify — a broken jar means stopping and clearing a wide area.

Keep glass in the prep and dry store areas and use plastic on the line. The plastic kitchen accessories range covers the alternatives.

Hot jars into a cold room is hard on the glass and on the room, which has to pull the heat back out of everything else. Let them come down first.

Cool on a rack or in a blast chiller if you have one, then move them into the cool room.