Fit decorating bag with decorating tip and fill 1/2 full or less with medium consistency
Hold the decorating bag at a 45° angle at 3:00 (9:00 for left-handed decorators) with tip slightly above the surface. Squeeze out icing with even pressure, curving tip down and around to the right as if writing a "c". (Left-handed decorators will pipe reverse c's like a comma shape by following the same procedure as above, just curving tip down and around to the left.) Relax pressure at the bottom of the "c" forming a "tail". Stop squeezing and pull tip away.
Reposition the tip at the same height as the previous "c" and repeat to complete the border, using a steady, even pressure.
To end, stop squeezing and pull tip away.
Hint: Create a two-tone wave look using blue and white icing in the same decorating bag, or stripe the decorating bag with icing color.