1. Wash the fruit. Slice the apples without peeling or coring. Add to the damsons and water.
2. Simmer gently until the fruit is thoroughly mashed.
3. Strain through a scalded jelly bag. Leave it to drip for 1 hour.
4. Measure the extract, return it to the cleaned pan and heat gently.
5. Weigh and add the required sugar (usually about 800g for each litre of extract).
6. Stir until dissolved, then boil steadily until setting point is reached.
7. Remove from the heat, skim, pot, cover, and label.
If the juice is very thick, a second extraction can be made with another litre of water, and the 2 extracts mixed together.