Aqua food colouring is available from some speciality baking stores but is not sold by most grocery retailers. The widely available four pack of food colours traditionally includes red, yellow, blue and green. Many different shades and colours can be made by using the food colouring alone or mixing them together in varying combinations and ratios. Achieve the perfect aqua colour for a batter or frosting by adding a little food colouring at a time in the correct amounts.
Add four drops of blue liquid food colouring to a small clear glass bowl.
Squeeze in a single drop of green liquid colouring and swirl the glass bowl gently to blend.
Hold the glass bowl an inch away from a light to look through the blend of colours and determine if any adjustments are necessary.
Increase the amount of green food colouring one drop at a time and check the colour with the light before changing the ratio. Make incremental corrections with a single drop of blue if the aqua colour gets too green.
Apply the aqua food colour directly to the food product it is intended to colour a quarter tsp at a time and blend thoroughly until the desired colour is achieved.
Pour left over aqua food colouring through a clean funnel into a small sterile bottle. Label and seal the blend to store with other colours. Shake the bottle for a few seconds before each use.