Mordants and Modifiers for Natural DyeingOur range of mordants and modifiers are essential to help you achieve rich, lasting colour from natural dyes. Used before or after dyeing, these essential materials improve colour fastness and allow you to shift, deepen, or transform shades naturally. Suitable for plant, insect, and mineral dyes, they give you greater control over your results—whether you’re aiming for soft, earthy tones or bold, complex hues. Ideal for fibre artists, textile designers, and anyone exploring the art of natural dyeing. Aluminium Potassium Sulphate (Alum)This high-quality alum is free from heavy metals and ideal for mordanting fibres and fabrics in natural dyeing. Most commonly used with protein fibres, it can also be paired with a tannin to effectively mordant cellulose (plant-based) fibres. Supplied in crystal form, alum dissolves easily in hot water for consistent, reliable results. Available in 100g or 500g resealable bags. Aluminium AcetateThis fine aluminium acetate powder is ideal for mordanting cellulose (plant-based) fibres in natural dyeing. It is commonly used in a two-step process with calcium carbonate (chalk), but can also be used on its own or in combination with tannin. The powder dissolves readily in hot water for even application. We recommend wearing gloves and a face mask when handling. Available in 100g or 500g resealable bags. Soda AshSoda ash, also known as sodium carbonate or washing soda, is used to scour cellulose (plant-based) fibres in preparation for natural dyeing. It can also be used as an alkaline post-modifier and as an alkaline agent in indigo or woad vats. Soda ash dissolves easily in hot water. We recommend wearing gloves and a face mask when handling fine powders. Available in 100g or 500g resealable bags. Calcium Carbonate (Chalk)Calcium carbonate, commonly known as chalk, is used in natural dyeing to help harden water, particularly when working with plant dyes such as madder. It is also commonly used in a two-step mordanting process for cellulose (plant-based) fibres in conjunction with aluminium acetate. Available in 100g or 500g resealable bags. Calcium Hydroxide (Hydrated Lime)This natural calcium hydroxide—also known as hydrated lime, slaked lime, or calx—is a versatile, high-quality material derived from limestone and water. It is valued in traditional crafts and ecological practices, and is especially important in natural dyeing for preparing indigo vats and supporting resist techniques. Available in 100g or 500g resealable bags. Citric AcidThis high-quality citric acid is a versatile modifier used in natural dyeing to adjust and shift colour. It is particularly effective for brightening hues, allowing reds to move toward vibrant oranges and purples to soften into pinks. Ideal for use as an acidic post-modifier when experimenting with colour variation. Available in 100g or 500g resealable bags. Cream of TartarCream of tartar is a gentle, naturally derived additive used in natural dyeing to improve colour clarity and brightness, particularly when working with protein fibres such as wool and silk. Often used alongside alum, it helps soften fibres and produce clearer, more even shades. Ideal for enhancing uptake and achieving vibrant, well-balanced colours in natural dye baths. Available in 100g or 500g resealable bags. Ferrous Sulphate (Iron Sulphate)Ferrous sulphate, also known as iron sulphate, is a versatile material used in natural dyeing to modify and deepen colours. It can be used as a mordant to help improve light- and washfastness, or as a post-modifier to shift tones, create greys and darker shades, and produce dramatic contrasts. It is also widely used in eco-printing and bundle dyeing, making it an essential tool in the natural dye studio for controlled colour transformation. Available in 100g resealable bags.
