And, since it's pre-colored, there's no need to worry about adding food coloring. Simply warm the icing in the microwave, then pipe it on your cookies straight from the bottle. Once decorated, let your cookies dry for 30 to 45 minutes before adding additional decorations. One bottle is enough to cover about 16 (3 in.) cookies. While this icing dries smooth, it does not dry hard (like royal icing). Icing will spread or smear if cookies are stacked.