Brighten your icing with Super White Icing Whitener by Sugarflair.
Add this fine powder to off-white buttercream, royal icing or marzipan to brighten. You can also add alcohol or water to make a white edible paint (perfect for that chalkboard effect on black sugarpaste).
Instructions: Add a small bit at a time to your icing and check the colour. Roughly one teaspoon to 250g of icing.