Calcium carbonate for natural dying
Calcium carbonate is a common substance found in rocks composed of the minerals calcite and aragonite. These are commonly found in limestone, a type of sedimentary rock consisting mainly of calcite. It is also the main component of pearls and shells of marine organisms, alongside snails and eggs. It is a white powdery mineral often used in the dying process to deepen shades of colour. It is also one of the principle minerals that create hard water and it can be added to paint to give body and density, as well as provide a white pigment on its own. It is widely available.
To dye deeper shades of red when using the plant root madder, calcium carbonate can be added to the dye bath for cotton dying. This binds with the madder and enriches the colour. For wool or silk, add some ammonia to your dye bath until the colour of the solution is reddish rather than orange.
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