Calx is also known as calcium hydroxide, hydrated lime or slaked lime. It serves as an alkali in many dye recipes.
It is used in indigo fermentation vats and serves to raise the ph level helping to dissolve the indigo and aid in the reduction of indigo .
It is also an ingredient in Nori paste (Japanese rice paste resist). It causes the starch molecules in rice flour to swell and give the paste body. It also acts as a preservative.
It is useful for numerous preparations. Hydrated lime is used for the preparation of indigo dyebath with iron and indigo organic dyebath, for instance with fructose syrup (e.g. 1-2-3 organic dyebath according to Michel Garcia’s recipes). Dipping your fabrics into lime water before dyeing with indigo will also enhance the shades.