If you've ever tried decorating a cake using icing to make the trunks of trees, sand at the beach or a wooden fence, you may have found it difficult to find or make the frosting brown. You will not typically find a brown food colouring without having to combine other colours to make it. Red and green food colouring will make brown when mixed into icing. Using paste or gel food colouring makes a stronger colour than the liquid kind does.
Choose paste or gel food colouring. Food colouring paste offer the most vivid colours and the widest range of colours to choose from although the thick paste can be a bit tough to work with. Food colouring gel is much easier to use than paste and it blends easier and provides strong colour, but not as strong as paste. Decide which paste to use based on how vivid and bright you need the colours to be for your baking project. Do not attempt to use the typical liquid form of food colouring found in the grocery store. Liquid food colouring is very weak and will not give you a strong colour without having to add a lot of food colouring which will make your icing taste bitter.
Determine the type of icing you are wanting to turn brown. Different ingredients in icing can affect how the colour will turn out. If you are using fondant, paste food colouring works the best. Any icing that contains butter or margarine will result in a darker colouring. Any acid in the icing, such as lemon juice or cream of tartar will leave the mixed brown colouring with a greenish tint to it, so it is best to not include acids.
Add equal amounts of red and green gel or to the icing. Mix well until the brown colour starts to appear. For a darker brown continue to add an equal amount of the green and the red. The total amount of food colouring you are to use depends on the amount of icing you are using for your cake decorating project. For gel or paste colours you should start with just a couple of streaks of food colouring on your icing using a flat toothpick at a time. Add more streaks and mix until you reach the desired brown colour.
Any icing that you colour that has perishable items in it such as milk or butter must be refrigerated. Coloured icing will turn darker over time, so if you are not serving the cake right away, go light with the food colouring, and check the colour the next day before adding any more food colouring. Light will fade your colouring, so keep the coloured icing away from direct sunlight and household bright lights. As an alternative to red and green colroring, combine about a 1/2 teaspoon of cocoa powder and a drop of yellow food with the icing to make a light brown icing, as an a more natural alternative. This will also give your icing a chocolate flavour. Use more cocoa powder for a dark colour.