Things You'll Need
Color printout of army green color
Bowl of white frosting
Blue-, yellow-, black- and white-gel food coloring
Army green has been a staple color for the militaries of many countries throughout the world. Getting the color right when making a cake may involve mixing your own frosting colors, if you cannot find a premixed food color that is suitable. Use gel food colors when coloring frostings, because liquid food colors disrupt the liquid ratio of your frosting. This can result in frosting that runs, or otherwise does not stay where you put it with your spatula -- a definite problem when decorating.
Open your blue-, yellow-, and black-gel food coloring containers. Gel food colors usually come in squeeze bottles or screw-top pots. Remove the lid of any color in a squeeze bottle, as it will only get in your way.
Stick a toothpick in each food color container. Then, pick up a small amount of yellow gel color on the end of the toothpick you stuck in that container. Drop it on top of your frosting in the bowl.
Add a slightly smaller amount of blue-gel color to the frosting in the same way, using a toothpick. Mix both colors into the frosting thoroughly with a spoon, then add a tiny speck of black-gel color and mix it in as well.
Consult your color printout of the army-green color you want to achieve, then compare your present color to it. Adjust the color by using small amounts of any of the three colors you already used. Make it lighter by adding a little white-gel food coloring, if the frosting is too dark.
Mixing frosting colors is a lot like mixing paint colors. Rules of color mixing work the same, no matter what the medium. If you have previous experience in mixing paints, even if it was just for an art class in grade school, the color wheel still applies and can help you here. In this case, yellow and blue make green, while the black make the color darker and drabber.