Saffron is used to both flavor and color a dish. Yellow food coloring is easily made through the use of saffron, and different shades of yellow uses different strength, or a mixture of saffron and other other colors. These authentic food color recipes come from The Complete Confectioner, Pastry-Cook and Baker, first issue published in 1849.
Infuse saffron in warm water, and use it for colouring any thing that is eatable. The English hay-saffron is the best; it is taken from the tops of the pistils of the crocus flower; it is frequently adulterated with the flowers of [marygolds] or safflower, which is known as the bastard saffron, and is pressed into thin cakes with oil. Good saffron has a strong agreeable odour, and an aromatic taste. Gum paste and other articles which are not eaten may be coloured with gamboge dissolved in warm water.
To make different shades of yellow, the author recommends:
Orange – Yellow, with a portion of red.
Gold – The same, but the yellow must be in excess.
Lemon – Use a solution of saffron.
Green – Blue and Yellow.