Use it for flowers with upright petals -if icing is not stiff enough, petals will droop. Medium Icing is used for flowers with flat petals and for borders -when the icing is too stiff or too thin, you can't get the uniform designs that characterize a perfect border. Thin Icing is used for writing, stems, leaves and for frosting a cake. The way your decorations curl and point and lie depends not only on the icing consistency but also on the way you hold the bag and the way you move it. Bag positions are described in terms of both angle and direction.
Angle refers to the position of the bag relative to the work surface.
Used when making stars or flat flowers or rosettes. Used for writing and borders. The angle in relation to the work-surface is only half the story on a bag position. The other half is the direction in which the back of the bag is pointed. Pretend that the circle you formed in the air is a clock face.