Practical Brown Iron Oxide Pigment: Grades, Properties and Selection Guide

What Is Brown Iron Oxide Pigment?

Brown iron oxide pigment is a synthetic inorganic colorant produced by intimately blending and co-milling yellow (goethite), red (hematite), and black (magnetite) iron oxide phases into a single uniform powder, commonly classified under CI Pigment Brown 6 or CI Pigment Brown 7.

Because it is a composite rather than a single oxide, the final hue depends on the ratio of base phases and the fineness of the grind. Industrial grades typically carry an iron oxide (Fe2O3) content above 90 percent, and a properly milled brown shows no visible segregation under a 100x microscope.

Typical Specification Ranges

The values below are what a well-run mill should hold across delivered lots. Always request a certificate of analysis per shipment, not a one-time data sheet.

For production buyers, the two numbers to check first are Fe2O3 content and moisture. Moisture above 1 percent will appear as poor dispersion in plastics and as mottled surfaces in concrete. Deqing Demei Pigment Technology Co., Ltd. offers its compound brown iron oxide in standard, micronized, and low-heavy-metal series, including the brown iron oxide pigment used most often for pavers and architectural coatings.

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Color Stability Is Decided by the Blend, Not the Color Card

Color stability in brown iron oxide is decided inside the mill, before the powder reaches your mixer; the ratio of yellow, red, and black base phases is the single biggest factor you can audit.

Yellow goethite is soft and oil-hungry, red hematite is dense and hard, and black magnetite is heavy and slightly magnetic. When a mill simply tumbles these powders together, the denser phases migrate during transport and the shade separates in your silo. Correctly made compound brown is co-milled until the particle-size distributions of all three phases overlap, usually with a D50 between 1 and 3 microns.

The practical consequence: specify micronized brown for plastics and powder coatings, where agglomerates form visible specks, and standard grade for concrete. For shade-critical work, our comparison of 686, 663, and 610 brown oxide grades shows how the same color number can hide very different hue angles.

Where Brown Iron Oxide Is Used in Production

Brown iron oxide is specified wherever a warm earth-tone color must survive sunlight, weather, and repeated mechanical abuse, and it is the pigment of choice for concrete, coatings, and plastics.

In concrete and construction, it delivers through-body color to pavers, roof tiles, and architectural blocks without bleeding or fading like organic colorants. In coatings, it is the base for wood stains, facade paints, and industrial primers because of its UV stability. In plastics, it is loaded into polyolefin masterbatch for garden furniture, automotive interior parts, and outdoor packaging.

Typical concrete dosage is 3 to 6 percent of cement weight. At that level, brown iron oxide does not reduce compressive strength; exceeding it only increases water demand.

Choosing the Right Grade: 686, 663, or 610

A brown iron oxide grade number encodes a hue family and a strength level, not a universal standard, so the right choice is made by comparing real color chips and running your own test batch.

686 is the workhorse dark reddish brown with the highest tinting strength and the best economics per kilogram for concrete. 663 is a yellow-brown with a softer, warmer tone, favored in architectural coatings and wood stains. 610 is a light reddish brown that produces clean tan shades but needs a higher dose to reach the same depth.

Do not rely on the grade number alone: two mills can both label a product 686 and deliver visibly different hue angles. To pull a 610 toward a yellow-tan, blend it with a heat-stable iron oxide yellow pigment; for a deep umber, add a small portion of red oxide.

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How to Qualify a Brown Iron Oxide Pigment in One Week

• Request a certificate of analysis with Fe2O3, moisture, pH, oil absorption, and D50 particle size.
• Make a 200 g test batch in your real system: concrete mix, mill base, or masterbatch.
• Measure delta-E against your approved master sample after 24 hours and again after one week.
• Run a 60-minute heat test at the maximum process temperature you expect.
• Scale to a trial lot and check color drift across three separate deliveries.

How to Vet a Brown Iron Oxide Supplier

A reliable brown iron oxide supplier is defined by three measurable things: control of base-oxide ratios, consistent moisture, and a certificate of analysis on every lot.

Because brown is a composite pigment, the supplier's real competence is in proportioning and milling, not in matching a color number. Ask three questions: Do you mill each brown shade from controlled base oxides? What is your lot-to-lot delta-E tolerance? Can you certify heavy-metal content on the low-heavy-metal series? The application guide on iron oxide pigment selection helps match these properties to your specific process.

• Certificate of analysis per lot: Fe2O3, moisture, pH, sieve residue
• Delta-E tolerance of 1.0 or better versus the approved master sample
• Confirmed lead time and production capacity for your order size
• Low-heavy-metal option for food-contact and sensitive applications
• Physical color card for shade approval, not a screen image

As a manufacturer rather than a trading house, Deqing Demei controls milling and quality testing on its own production line, and the full iron oxide pigment portfolio is available for cross-shade supply planning.

Frequently Asked Questions