1.Sift the icing sugar through a very fine sieve. Lightly beat egg white in a small bowl with a wooden spoon; add icing sugar, a heaped tablespoon at a time, beating well after each addition.
2.When icing reaches the desired consistency, add juice; beat well. Cover surface of icing tightly with plastic wrap while not using to prevent crust developing. Icing will harden considerably on standing. For a slightly softer icing, add a few drops of glycerine to the icing.
Royal icing dries hard which makes it perfect for detailed decoration of cakes and cookies. For best effect, apply royal icing using a piping bag.Note