There are many ways of colouring soaps ranging from an essential oils (orange, for example) to chemical dyes. Merri Creek Soaps does not use any chemical dyes. The following is a list of colourants that we do use.
Titanium dioxide is a naturally occurring pigment which is mined and refined to remove impurities. It is an opacifier used incredibly widely in the food, cosmetic and personal care and paint industries. There has been some concern about the possibility of absorbing nano particles through the skin, but the greatest danger seems to be from breathing it in.
Zinc oxide is another opacifier and is widely used in a number of formulations. It also soothes skin which is why it is used to help treat nappy rash. We use it in our soap precisely because of those skin soothing properties.
Oxides and Ultramarines used to be mined, but due to concerns about their purity they are now created in labs.
Micas belong to a group of naturally occurring minerals that are mined and then pulverised into the finest of powders. This powder is then coloured with oxides and pigments to achieve a good range of colours. In terms of purity they are the least natural that we use to colour soap. But they do give such lovely bright colours that it would be hard to say goodbye to them.
Clays are lovely to use in soap. All our soaps contain kaolin clay as it is a useful skin detoxifying and cleansing agent. Other clays we use are Cambrian blue clay (from Siberia), French pink clay, French green clay, French yellow clay, Brazilian yellow clay, Brazilian purple clay, Australian red clay, Australian blue clay and there's a few more we have tried out yet. All the clays give soap a lovely feel and each has different properties for use on the skin.
Natural colourants are many and varied: turmeric for yellow, cinnamon to give a rich brown, activated charcoal for black and shungite also for black, Madder root powder is for a range of pinks, indigo for blue, spirulina powder for green and woad which we haven't yet managed to get a really great blue colour from. That list is also far from exhaustive. Using carrot juice as the liquid component of the lye gives an orange soap - something else that's on the list to be tried out.