Pigment & Iron Oxide

Frequently Asked Questions

• What colours are available in Domcrete's iron oxide range?

  Domcrete stocks different iron oxide colour pigments covering a spectrum of concrete colour work:

  • Black Iron Oxide – deep, charcoal black with a cool undertone; the most commonly used concrete pigment for charcoal, dark grey, and a range of deeper grey tones.
  • Warm Grey Iron Oxide – a soft, neutral warm grey with subtle beige undertones, This blend has been specifically formulated with iron oxides to counteract cool tones, making it the closest match to the appearance of natural concrete.
  • Brown Iron Oxide – warm earthy brown, ideal for natural and earthy colour tones.
  • Light Red Iron Oxide – a warm brick-red tone with good tinting strength, ideal for terracotta and earthy palettes.
  • Dark Red Iron Oxide – a deeper, rich red with strong earthy terracotta tones suited to bold feature pieces and industrial or raw-earth aesthetics.
  • Yellow Iron Oxide – warm yellow, producing sandy, ochre, and beige tones.
  • Jade Green Oxide – rich jade green, ideal for distinctive feature applications.
  • Ultramarine Blue Oxide – a deep, vibrant blue, for bold and statement colour pieces.
  • Titanium White Oxide – bright white, used to lighten mixes and create brighter white and pastel tones.

  For colour selection advice or to discuss blending multiple oxides to achieve a custom colour, contact the team.

• How much iron oxide pigment do I need per mix?

  Dosage rates for iron oxide pigments in concrete typically range from 1% to 10% by weight of cementitious content. As a general starting point when casting with the Alpha Premix range:

  • 2-120g per 20kg bag – subtle tint; best for very pale or pastel tones
  • 120-350 per 20kg – Subtle depth, light to moderate colour saturation; suitable for soft, natural tones
  • 350-600g per 20kg bag – Rich, noticeable colour; a popular range for achieving stronger, more defined tone
  • 600-800g per 20kg bag — Deep, highly saturated colour; increasing pigment beyond this range generally provides diminishing colour returns and may negatively affect strength

  For accurate dosage recommendations for your specific premix formula, refer to the product page for each pigment or visit the Knowledge Hub for mix design guidance. Always weigh pigment accurately as volume measuring introduces inconsistency between batches.

• Can I use iron oxide pigment powder in a GFRC or ECC premix?

  Yes. Iron oxide pigment powder is fully compatible with all GFRC, SCC, and ECC mix designs, including Domcrete’s Alpha premix range. The pigment is added dry to the mixer before or during the initial dry-blend stage, prior to adding water and admixtures. Because the Alpha premixes use white cement as their base, they provide an ideal neutral canvas for pigmentation, producing cleaner, truer colour results than grey cement-based mixes. Consistent dosage weighing and thorough mixing time are critical to achieving even colour distribution. See the GFRC Applications gallery for examples of pigmented concrete in use.

• Do I need to seal pigmented concrete?

  Yes. Sealing is essential for all pigmented concrete, regardless of the colour or mix type. Although integral iron oxide pigment is chemically stable within the matrix, the surface of an unsealed concrete piece will absorb oils, moisture, and contaminants that can alter the perceived colour and cause staining over time.

  Your choice of sealer also affects the final colour, so it’s worth factoring in before you settle on a pigment dosage. Alpha X, for example, is a colour-enhancing sealer and can deepen the finished colour by around 2 to 3 shades, turning deep charcoal to black. This means unsealed concrete won’t always show the true final result. Where possible, seal a small test sample first to check the colour before committing. Browse our full range of sealer and sealer prep products to find the right system for your finish.