Iron oxide red

Iron oxide red (CAS 1309-37-1), also sold as C.I. Pigment Red 101 and red oxide, is a synthetic or naturally derived inorganic pigment. E172(ii).

Where is Iron oxide red used?

• Architectural and industrial coatings: color and passive barrier against substrate corrosion
• Marine and infrastructure environments: reduces coating system failures
• Concrete, paving blocks and fiber cement: mass-toning pigment for fade-resistant earth tones
• Automotive OEM and refinish primers: corrosion-inhibiting functional component
• Printing inks and packaging coatings for construction materials: heat-stable, non-bleeding color
• It imparts color and corrosion resistance in industrial and consumer applications.
• Used as a pigment in colored asphalt.
• Used in brake pads.
• Used in the paper industry.

Good to know: Synthetic grades offer tighter particle size distribution and higher tinting strength than natural grades.

Formulation notes

• For liquid binders, add liquid slowly to the pigment and mix to a smooth paste to avoid flocculation.

Typical specification

• Tinting strength of 95–105%.
• Grade Red 110 has an oil absorption of 15-25 g/100g.
• Light fastness of 8 on a scale of 1 to 8.

Regulatory status

• Not classified as a hazardous substance according to EC 1907/2006 and EC 1272/2008.
• In the EU, the use of iron oxides in food contact products is governed by Regulation (EC) 1333/2008 and its amendments for specific food additives.

Storage, packaging and handling

• Store in a dry, covered, well-ventilated place, keeping containers tightly closed to prevent moisture absorption.

Frequently asked questions about Iron oxide red

How does water soluble salts content affect the use of iron oxide red in construction materials?

Standard grade has water soluble salts content of 0.3% or less. Low water soluble salts content is vital to prevent efflorescence in red bricks or pavers.

What are the compatibility considerations for iron oxide red in cement-based applications?

Neutral pH ensures it won't interfere with cement hydration or setting time in concrete applications. For dry binders such as plasters and cements, it may be added directly to the dry ingredients before mixing.

What are the durability characteristics of iron oxide red?

It has high UV, weather, and chemical resistance. Spherical particles provide better dispersibility, reducing high-shear mixing time and energy.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.