How Do I Make Icing Harden?
To make icing harden, you can add powdered sugar or cornstarch to the icing mixture. Alternatively, you can refrigerate the icing or place the baked goods with the icing in the fridge or freezer. Another option is to add a hardening agent such as meringue powder or agar to the icing. These methods can help the icing form a firm and glossy finish.