Jar sealing is an essential skill when it comes to storing your preserves. Knowing how to seal jars correctly will give your preserves a good start in life and help prevent spoilage. You should seal a jar as quickly as possible once you have filled it with your preserve. Doing so will prevent oxygen and nasty airborne micro-organisms getting in.
When sealing jam jars filled with sweet jams, chutneys or relishes, you generally have two methods of sealing to choose from: cellophane covers or twist-on lids. Here at Preserve Shop, we prefer to use twist-on lids, but each method has its advantages and disadvantages.
Sealing Jars with Cellophane Covers
Sealing jars with cellophane covers gives a nice traditional finish to your preserves. However, this method is not always practical if you plan to give your preserves as gifts and the contents of the jar may be shook aroud.
For this method you will need waxed discs, cellophane covers and elastic bands.
After potting your preserve, while it is still hot, place a waxed disc with the waxed side down on top of the hot preserve within the jar. You should ensure that the whole of the disc is in contact with the preserve and there are no air bubbles underneath it. This part can be a little tricky but is essential to ensure a good seal. Before you carry on, make sure the rim of the jar is free from any traces of preserve. Next, moisten one side of the cellophane cover with a drop of water or two and place it, with the damp side facing upwards, on the jar. Then secure the cellophane cover with an elastic band and leave to dry; as the cover dries, it will contract and form a tight seal. This whole process should ideally be carried out whilst the jar and its contents are still quite hot; sealing whilst the jar is only warm may lead to the growth of mould. However, it is possible to apply the cellophane covers when the jars have completely cooled.
Sealing Jars With Twist-On Jam Jar Lids
Sealing jam jars with twist-on jar lids is the most reliable way to seal jars. It is also the simplest and easiest way. Screw-on lids create a really good seal and it won't matter if you are transporting your produce as the lids won't get punctured or come loose.
For this method all you need is a correctly sized twist-on lid for each jar.
After potting your preserve, ensure the rim of the jar is clean and simply twist on a lid tightly to seal the jar.
The best lids, also the most widely available, are the kind with a plastic lining inside them that complies with various food regulations and legislation. These types of jar lids are suitable to use with both sugar-based preserves and vinegar-based preserves. Unlined metallic jar lids should never be used with vinegar-based preserves such as pickles and chutneys as the acid in the vinegar will corrode the lid and your precious preserve will be spoilt.
Whereas jars may be reused (see Reusing Jars), jar lids should ideally be used only once as they become tainted.