There are a number of ways of sterilising glass vessels of one kind or another for keeping cordials and preserves.
The dishwasher or the microwave method
Some people sterlise their glass preserving jars and bottles either using a super-hot dishwasher setting or in the microwave (clean, rinse, leave the jars wet, put in the microwave on high for 60 seconds, remove with oven gloves and leave to cool).
The Aga method
Because I have an Aga I find putting the jars and bottles carefully in the top left oven for twenty minutes is the easiest way.
The oven method
Those without an Aga can replicate this by simply heating their oven to 130°C.
Some people put newspaper on the oven racks but I never bother with this.
On removing the glass from whatever you have heated it in
Take the glass out of the dishwasher, microwave or oven (with oven gloves of course) and leave to cool completely.
Fill with cold liquid or preserves.
Don’t forget the lids or corks
Metal lids should be boiled for ten minutes – but you should avoid metal for anything acidic.
Alternatively, metal stoppers lined with heatproof plastic, or other plastic/rubber type stoppers should be washed thoroughly in hot soapy water, rinsed well, then put on a tray in a very low oven (120°C) to dry out and heat up.
Corks should be boiled for an hour – and once inserted, covered with melted parafin wax. Very vintage look!