I have made watermelon pickle "like your grandmother's" for 40 years having acquired the recipe from my mother-in-law. My friends and neighbors and family all love it. Originally she used Lilly's Lime Powder made b y Lilly Pharmaceuticals. They stopped making it about 20 years ago. Since then I have used Mrs. Wages Lime Powder which is available in grocery and hardware stores that have canning supplies - and also on line. The two products are obviously different because the recipe calls for a tablespoon of one and a cup of the other. The Lilly's was called "slaked lime". Although I do not think the ones made with Mrs Wages are quite as crisp, they are still quite good! I have tried using recipes in cookbooks that call for a salt water soaking and it is not the same at all! I saw your question while trying to locate a source for the "slaked lime" that Lilly's once sold.