Use electric mixture and cream butter or shortening well.
Add flavoring, salt, and powdered sugar.
Continue to blend with mixer, adding liquid a little at a time (only enough to be able to blend easily).
It will be heavy at this point.
When all the sugar is well blended, stop the mixer and test consistency. It should be stiff enough to hold its shape when a knife drawn through it.
You may not use all the liquid. It is better to add a little more later if needed. The proper texture should be fluffy, with a consistency of heavy whipped cream, but not bubbly. Overbeating, with too much liquid causes air bubbles, making holes in the finished decorations.
If accidentally you add too much liquid, it can be corrected by the further addition of sifted powdered sugar.
If, after the decorating processes have been started, you find the consistency too soft or too stiff, it is not necessary to return the icing to the mixer. Just blend the cream or powdered sugar with a fork in the bowl.
This icing keeps well under refrigeration for many weeks if tightly covered.
Bits of leftover colored icing may be wrapped separately in waxed paper and placed in an airtight plastic bag tightly sealed with a rubber band and placed in the refrigerator for use at a later date.
Be sure to warm it to room temperature before using and fluff with a fork to restore proper consistency.
Use paste colors sparingly, as the colors darken upon standing. Adding too much paste color may also cause a slightly bitter taste.
When using butter, watch the liquid addition carefully. There is more moisture content and a lower melting point which means it will soften faster with the heat of the hands. The flavor of butter is much better than shortening. The colors of frosting are affected by the yellow color so if you want white frosting, it's best to stick to shortening.