You can still start with a white icing, but you will probably have to add flavoring later to cover the bitterness of the dye. You can dye most icing–including buttercream, cream cheese, or royal icing–black by following these instructions. Because royal icing is white, you may need to add flavoring or cocoa powder to hide the bitter flavor.
If you cannot find black dye, mix equal parts red, blue, and green food coloring. You won’t get the “true” black like you would from the store-bought black, but you can achieve a very dark gray that can pass for black.
To thicken, thoroughly mix in some sifted powdered (aka confectioner’s) sugar. [1] X Research source If you don’t want your icing any sweeter but it’s not thick enough, add some meringue powder instead. [2] X Research source If you are using royal icing, drag a butter knife through the surface. Count how long it takes the icing to smooth back over. If it’s between 5-10 seconds, your icing is thick enough. Any faster and you need to mix it longer or add a little sifted powdered sugar or meringue powder. [3] X Research source
You may also want to wear an apron so you don’t get any dye on your clothes.
The color will continue to deepen even once you’ve piped it onto a cookie or cake, so if you are super short on time you can go ahead and decorate immediately. Just be aware you won’t have the opportunity to troubleshoot if the icing doesn’t develop into the black you want. [7] X Research source Keep the icing out of direct light as it develops, as this can cause the black to fade. [8] X Research source
You can also avoid this problem by using black only sparingly. Try to use it just for accents and outlines.
Cocoa powder will give your icing a chocolatey taste and will help darken the color, too. In a small bowl mix 1/2 cup of cocoa powder with 2 teaspoons of water (so it won’t make lumps in your icing). If it’s still bitter, add another 2 tablespoons (29. 6 ml) of cocoa powder. [10] X Research source Add a strong flavor, like cherry or orange, to your icing. Use about 1 teaspoon per 2 cups of icing. [11] X Research source If you can’t have cocoa, substitute with carob powder.
If your black has a green hue, add red food coloring one drop at at time. If your black has a purple hue, add green dye one drop at a time.
Avoid storing your cake or cookies in the refrigerator or an air-tight container at room temperature, as this can cause condensation and make your colors bleed. [13] X Research source Try to use as little dye as possible when mixing your black. If you use too much, you can thin out the icing, which can cause it to bleed. If you have already added too much black dye, try thickening with a little powdered sugar. You will probably also want to flavor the dye to cover the bitterness of too much black.
