Jars and covers for preserves

Wash empty jars in warm soapy water and rinse well with running hot water, or wash in a dishwasher. Unrinsed detergents may cause unnatural flavours and colours. These washing methods do not sterilize jars, see below. Sterilize lids and covers in boiling water for ten minutes, keep lids in hot water until ready for use. then rinse and dry, do not wipe jars or lids with tea towels. Use only fresh kitchen paper towels to dry lids.
Place jars upside down on kitchen paper towel to drain, Pre warm oven, set on its lowest setting, place jars upright on oven tray, place in oven twenty minutes before required. The time when jars are prepared will depend on recipe.
When filling, most jams are allowed to cool, this is also the time to turn off oven. Hot jam mixture potted into hot jars will lead to the fruit rising to the top, spoiling the appearance of the finished product. If making jellies or curds, then the mixture is potted straight away as any delay will cause the jelly to begin gelling in pan. Hot jars are placed on a wire rack to prevent cracking, also allow jams to cool overnight by standing on a heat resistant table mat.

Sterilization of empty jars

It is possible that you will be given used jars. Discard any that are chipped or defective in any way, if standard 227g / ½ or 454g / 1 lb jam jars, then discard any that have commercial-trade marks. Discard all lids, use new one.
To sterilize empty jars, place them in a large saucepan which has some sort of loose rack (to prevent jars contacting bottom of pan). Place them right side up, fill the saucepan and jars with hot (not boiling) water to 25mm / 1 inch above the tops of the jars. Boil for 10 minutes. Use food tongs to remove hot jars allow to drain. Scale or hard water films on jars are easily removed by soaking jars for 2 hours in a solution containing one cup of strong vinegar (5% acidity) per gallon of water. Store until required. Note! Jar cleaning will still be needed, before using for jam making, see above.