What you need100g (4 oz) of pure soap flakes
2 small lemons
1 large tsp of Alum (available from pharmacies)
Chop the lemons up into small pieces and remove the pips.
Place into a blender or a mortar and pestle along with the soap flakes and alum and crush together until a stiff paste is formed.
Roll the mix into balls and place on greaseproof paper and place in a dry dark place to harden for around 7 days.
To use just rub onto the stain and either soak or place into the wash.