Ferrous Sulphate (Iron)

Ferrous Sulphate – for shifting and deepening colour

Ferrous Sulphate (iron) is used in natural dyeing to modify colour. It works as a saddening agent, darkening tones and shifting colours towards greys, greens and deeper, more muted shades.

It is commonly used after dyeing as a separate bath, or added in small amounts to a dye pot to alter the final result. A little goes a long way.

Ferrous Sulphate can also be used in combination with tannin and alum when mordanting plant fibres, particularly where darker tones are desired.

Suitable for

Silk, wool, cotton, linen and other plant-based fibres

Why use it

• Darkens and mutes colour
• Shifts yellows to olive, reds to plum, and brights to greys
• Expands your colour range from a single dye source

Usage guide (WOF)

0.5–2% WOF for colour modification; up to 4% WOF for stronger darkening (use lower rates on silk and wool)

Use with care

• Always use in low concentrations
• Overuse can weaken fibres, especially protein fibres like silk and wool

A useful addition for natural dyers wanting more control over tone and depth.