A box of food coloring usually contains four choices: red, yellow, blue and green. But if the green isn't dark enough, or the color you're going after isn't included, you'll have to become an artist and mix the colors yourself. This is where the science of color comes in, and while the proportions may seem excessive, just remember that 100 drops of liquid food coloring is the same as 1 teaspoon. The color formulas work on homemade frosting as well as store-bought, and with the appropriate ratios, you'll get dark green icing.
Don't use vanilla essence in your buttercream frosting mix – it'll change the color you want to achieve.
Types of Food Coloring
Liquid food coloring is an all-around coloring agent, good for dough, cakes and cookies. Because its base is water, the color isn't intense and tends toward pastel. You'll use more liquid food coloring to create your favorite color than you would with other types of food coloring.
Recent to the market, gel food coloring is in the baking aisle along with the liquid coloring. Gels have a base of water plus corn syrup or glycerine, giving them a thickness and a more intense color than the liquids. You'll need less gel than liquid, so test it before using it. Use the ratios of the formula you want and whip up a test batch before icing your cake or coloring candies.
Natural coloring has withstood the test of time and history. Created from plants, these dyes contain saffron, turmeric, beets and carrots. The colors are not intense; instead, they're subtle like the colors found in nature.
St. Patrick's Day and the Christmas holidays are when you typically need to create dark green icing. Unless you're working with professional food coloring that comes in a variety of colors, you have only the four in your package to play with.
Buttercream icing is a standard frosting that accepts color easily. Cream cheese frosting is much whiter as a base, and it may take coloring more easily. Experiment as you go with small quantities of the color until you reach the intensity you're after.
Mixing food coloring to achieve green hues starts with 2 cups of buttercream frosting. Use 54 drops of blue liquid food coloring and add 27 drops of yellow. Adjust the intensity, knowing that the more yellow you add, the lighter the icing. If you're using gels, start with a small amount of blue, drop it in carefully, and mix.
Mixing the Food Coloring
A spatula is the best way to mix in the colors for your frosting. Add your color and mix in a figure-eight pattern until all the color is blended into the icing. While one hand is working the spatula, use the other to turn the bowl counter-clockwise. And don't forget to scrape the icing at the bottom of the bowl.
Maturing the Color
An intense color needs time to mature in the icing. After you've colored the icing, let it sit for a few hours. You'll see the color deepen as time passes.
When mixing colors to create a deep green or any deep color, gel gives more intensity than liquid and won't dilute your icing. If your green is getting too yellow, pull back on the yellow coloring and focus on the blue.
Use cocoa powder in your buttercream icing to create brown; to make it more intense, use dark chocolate powder. For black icing, start with a dark brown shade and find a black coloring at your local bakery supply store.
Beware of using lemon flavorings in your icing. The lemon is acid-based, and it affects the coloring, especially if you want a darker color or brown.