DIY & Supplies

Iron Oxide Pigments for Concrete Casting — A Practical Guide

Permanent colour that goes all the way through the material. What iron oxides are, how to use them correctly in concrete, and what the common mistakes look like.

By Juliet Duncan, BPharm  |  J.C. Epiphany Limited, Jamaica

Iron oxide pigments are among the oldest colourants in human history — they are the same compounds responsible for the reds, yellows, and browns in cave paintings that have lasted tens of thousands of years. That permanence is exactly why they are the preferred colourant for concrete casting. The colour does not fade in sunlight, does not wash out in rain, and does not react with the alkaline environment of cement the way organic dyes do.

For makers working in Jamaica and the Caribbean diaspora in the USA and Canada, iron oxides are also one of the few colourants that perform reliably in a hot, humid outdoor environment. They are mineral-based, chemically stable, and bond permanently into the concrete matrix during the curing process.

"Iron oxide pigments colour the concrete itself, not the surface. The colour is throughout the entire cast — it does not fade, chip, or wash away because there is no surface layer to remove."

The Colour Range

J.C. Epiphany stocks twelve iron oxide colours, covering the full spectrum from earth tones to saturated hues. Each is available for purchase individually for both concrete and cosmetic soap use.

Barn Red

Charcoal Grey

Coral

Dark Blue

Dark Green

Green

Honey Yellow

Light Blue

Mauve

Mustard Yellow

Squash Orange

Turquoise

Using Iron Oxides in Concrete

In concrete casting, iron oxide pigments are added to the dry cement mix before water is introduced. This ensures even distribution throughout the material rather than surface staining. The colour achieved depends on three factors: the pigment colour, the use rate, and the base cement colour — white Portland cement produces truer, more saturated colours than grey Portland cement.

Desired Intensity Use Rate (% of cement weight) Notes
Subtle / pastel 1% to 2% Best on white Portland cement base. Results in soft, muted tones.
Medium / standard 3% to 4% Balanced colour depth. Most commonly used rate for decorative pieces.
Deep / saturated 5% to 6% Maximum recommended rate. Beyond 6%, additional pigment does not deepen colour and can weaken the concrete mix.

Important — Do Not Exceed 6% in Concrete

Iron oxide pigment added beyond 6% of cement weight begins to interfere with the cement hydration process. The colour does not continue to deepen but the structural integrity of the cast can be compromised. For decorative pieces this may not cause visible failure, but the piece will be more porous and fragile than intended. Stay within the 1% to 6% range.

These Pigments Are for Concrete Use Only

J.C. Epiphany iron oxide pigments are supplied for concrete casting and decorative concrete projects. They are not assessed, tested, or recommended for use in soap, cosmetics, or any skin contact product. If you are looking for colourants for handmade soap, those require cosmetic-grade ingredients that have been through appropriate safety assessment — a separate category of product entirely.

For concrete use, the pigments perform exactly as described throughout this guide — permanently, reliably, and without the fading or bleed that organic dyes produce in an outdoor environment.

Colour Mixing — Getting Shades Beyond the Range

Colour Mixing Guide

Practical Tips for Working With Iron Oxide Powders

Iron oxide powders are fine and will temporarily stain skin, work surfaces, and clothing. Wear gloves when measuring and mixing. Work on a covered surface. The staining on skin washes away easily — it is the work surface and clothing that are more permanent.

Store pigments in sealed containers away from moisture. Although iron oxides are chemically stable, clumping from humidity makes accurate measurement harder and can cause uneven colour distribution in your mix. A dry, sealed container keeps them in working condition indefinitely.

Always measure by weight rather than volume for consistent results between batches. A teaspoon of pigment varies significantly in actual weight depending on how densely the powder has settled. A small kitchen scale accurate to 0.1g is the right tool for soap making quantities.

Iron Oxide Pigments — Available in Jamaica

Twelve colours, cosmetic and concrete grade. Sold individually. Available islandwide and ships to USA and Canada.

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Juliet Duncan, BPharm

Juliet is a pharmacist and founder of J.C. Epiphany Limited (formerly Epiphany Farms), Jamaica. Est. 2013. She supplies iron oxide pigments and raw materials for concrete makers and soap makers across Jamaica, and uses the same pigments in her own handcrafted concrete décor range.

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