Making maroon coloring for baking decorations involves mixing concentrated food coloring pastes with prepared white buttercream icing. The true red coloring, called red-red, might cause a bitter taste when used in large quantities such as on a cake. A red no-taste coloring can be substituted in such cases.
Create a small test batch to experiment with the shade you want for the final product. Place a heaping spoonful of white buttercream icing into a small bowl. Add in red-red or red no-taste and burgundy food colors at a ration of four parts red-red to two parts burgundy. Add colors slowly, stirring until combined.
Repeat the process with the rest of the icing once you've found the perfect equation for the color of maroon you want to achieve. Add in white-white coloring if you accidentally make the icing too dark. Keep in mind that buttercream icing will deepen in color as it sets.
Store the iced baked goods in a cool, dark place until ready to serve to preserve the color of the icing.