Mustard Yellow Iron Oxide Pigment

Mustard Yellow Iron Oxide – Synthetic Mineral Pigment (PY42)

Synthetic yellow iron oxide pigment | Warm mustard-yellow colour | Pigment Yellow 42

TerraChrom Mustard Yellow Iron Oxide is a synthetic inorganic mineral pigment made from yellow iron oxide hydroxide (α-FeOOH). Its rich, earthy mustard-yellow colour makes it an excellent choice for colouring compatible paints, limewash, plasters, mortars, concrete, and decorative finishes.

With high pigment purity and controlled colour consistency, Mustard Yellow Iron Oxide offers dependable colouring performance for applications where repeatable colour development is important. Its relative tinting strength is 95–108% in titanium dioxide reduction testing and 95–105% in barytes testing, compared with the respective reference standards.

This versatile pigment can be incorporated into water-based, oil-based, and mineral binders using suitable dispersion methods. Final colour, compatibility, and durability depend on the selected binder, pigment concentration, substrate, and application conditions.

Key Features

• Warm mustard-yellow colour – Produces earthy yellow tones in compatible paints and mineral finishes.

• Synthetic iron oxide pigment – Composed primarily of yellow iron oxide hydroxide (α-FeOOH).

• High pigment purity – α-FeOOH content greater than 99.2% (technical guide value).

• Controlled colour consistency – Defined colour tolerances for repeatable results under standardized testing.

• Reliable tinting strength – Relative tinting strength of 95–108% in TiO₂ reduction testing.

• Versatile applications – Suitable for formulation testing in limewash, paints, plasters, mortar, concrete, and decorative coatings.

• Fine powder form – Supplied as a dry pigment for incorporation into compatible binders.

Recommended Uses

• Limewash and mineral paints, subject to compatibility testing

• Decorative plasters, stucco, and mineral finishes

• Concrete, mortar, and cement-based products

• Acrylic and other water-based paints

• Oil-based paints, decorative glazes, and coatings

• Interior and exterior architectural finishes, subject to finished-system testing

• Artistic and restoration applications using compatible binders

Technical Information

Pigment name: Mustard Yellow Iron Oxide

Colour Index: Pigment Yellow 42 (PY42; C.I. 77492)

Pigment type: Synthetic inorganic iron oxide hydroxide

Chemical composition: Iron hydroxide oxide yellow (α-FeOOH)

CAS number: 51274-00-1

EC number: 257-098-5

Pigment content: Greater than 99.2% α-FeOOH (technical guide value)

Colour: Mustard yellow

Form: Fine yellow powder

Density: Approximately 4.0 g/cm³ at 20°C

Bulk density: 300–1,000 kg/m³

Tamped density: Approximately 0.4–0.8 g/mL

pH: 3.5–7.5 (5% suspension)

Oil absorption: Approximately 43 g/100 g pigment (guide value)

Moisture content: Less than 0.5% (technical guide value)

Water-soluble content: ≤0.5%

Solubility: Insoluble in water

Particle characteristics: Predominantly rod-shaped particles, approximately 0.1 × 0.7 µm (guide value)

Relative tinting strength: 95–108% in TiO₂ reduction; 95–105% in barytes testing, relative to reference standards

Mixing & Application

Mustard Yellow Iron Oxide can be incorporated into compatible mineral, water-based, and oil-based binders to produce warm, earthy yellow finishes.

For limewash and water-based paints, gradually incorporate the pigment using suitable wetting and dispersion methods to achieve a uniform colour. For cement, mortar, and other dry mineral mixes, distribute the pigment evenly throughout the dry ingredients before adding liquids.

For oil-based paints and decorative glazes, use an appropriate grinding or dispersion method for the selected binder. Always check colour development and compatibility before preparing larger quantities.

Recommended pigment dosage: No universal dosage is specified in the available technical documentation. Determine the appropriate concentration through small trial batches based on the desired colour, binder, and application requirements.

Always prepare a small test batch to evaluate colour, dispersion, compatibility, and finished-surface performance before proceeding with a larger project.

Handling & Storage

Store in a tightly closed container in a cool, dry, well-ventilated location, protected from moisture and direct sunlight. Avoid storage above 120°C, as pigment dehydration may alter the colour.

Avoid generating or inhaling airborne dust. Ensure adequate ventilation and wear suitable eye and respiratory protection when necessary.

Mustard Yellow Iron Oxide is not classified as hazardous under the Canadian Hazardous Products Regulations (HPR), based on available product information. Standard precautions for handling mineral powders should nevertheless be followed.

Refer to the current TerraChrom Safety Data Sheet for detailed safety and handling information.

Technical Documents

Safety Data Sheet: English | Français

Tech Sheet: English | Français