From 1922:

Make a lye by using 3 lb. of fresh wood ashes, 6 oz. fresh quicklime, und 6 quarts of cold water. Boil them together for 30 minutes. When the olives are full grown, but quite green, gather them carefully without bruising. Put them in a clean vessel, which must not be made of iron, and pour over them sufficient strained lye, slightly warm, to cover them well. Let them soak for about 30 hours. Pour off the lye, rinse the olives well with fresh, cold water, and keep them for three days in cold water, changing it two or three times a day. Then pack them in bottles, and cover them with cold brine strong enough to float an egg. In place of the wood ash lye, four ounces of caustic soda to one gallon of water may be used.