Yes, they sell it at the UK online store Partyrama. - NO THEY DON'T SUPPLY IT
It is also sold by the US site Sugarcraft. After checking their shipping policies, they do ship internationally to ". . . all countries in agreement with the US Postal Service". It's quite likely that the UK is one of them.
by adding orange food coloring to white icing
Using white icing you will have to add blue food coloring to it.
real red food coloring
food coloring
You can't make white food coloring, but you can get a commercially made icing whitener. It is used in cake icings when the butter in it causes the icing to be more of an off-white or pale yellow color. It can also be used to lighten the color of a cake icing if too much food color was used. It could also be used in other foods, as well, either cooked or uncooked foods. You can get it at many grocery stores, and also a stores that sell cake decorating supplies, such as Michael's. The one I use is made by Wilton.
Icings are colored with food coloring then applied to baked and cooled cupcakes. The food color from the icing does not ordinarily seep into the cake. If that is a problem, it is possible to apply white icing to cupcakes, then spray food coloring with an airbrush onto the surface of the icing, so it would not come into contact with the cake itself.
According to two cake decorators, no. Use a white frosting and color it blue, or a white frosting and airbrush it.
Edible food colouring is used to artificially colour food. One instance is that Cochineal is a red colouring that can be added to white icing to produce red or pink icing for decorating cakes.
Red mixed with a little water will make a pink color. If you are making icing, add a drop of two of red food coloring to white icing in order to turn the icing pink.
brown food coloring
physical change You are making a mixture of the icing and food coloring, which is a physical change.
Royal Icing is not a brand of icing to be purchased. It is made by using a recipe. It dries to a hard white, shiny gloss. Adding food coloring will make different colors.