How does malachite adhere to fiber such as wool, silk, nylon, and cotton?

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Malachite is a copper carbonate hydroxide mineral with a vibrant sea-foam green hue that was used early on to manufacture copper metal. It's chemical composition is denoted as Cu2(CO3)(OH)2.

Malachite's high degree of softness and malleability as well as a resistance to fading from time or light has led to its use as a dying agent across many cultures for thousands of years. Textile industries in particular used the pigment derived from this mineral to dye a wide range of fabrics including silk, wool, nylon, and cotton.

The pigment that is created from malachite— appropriately called "malachite green"—is a triarylmethane dye, which is a hyper-colorful synthetic compound using a basic skeleton of triphenylmethane.

Triphenylmethane makes the malachite green pigment soluble in non-polar organic solvents, although it's not soluble in water. Non-polar solvent dyes like malachite green will form ionic bonds with surfaces that have large numbers of polar sites.

Fabrics like silk, nylon, and wool boast an abundance of anionic polar sites (those with a negative charge), which readily and easily form bonds with the malachite green's cationic sites (those with a positive charge), making these fabrics easier to dye. Cotton and linen are composed of cellulose fibers that have far less anionic polar sites than the others, meaning they are more difficult to dye because the bonding attraction is weaker.

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