Fibre Reinforced Facade Encyclopedia: Finishes
Integral colour is colour produced by pigmenting the material itself, so that the colour runs through the section rather than sitting on it as a film. In a cementitious panel the pigment is batched with the mix and colours the cement paste; in a fibre reinforced polymer panel the equivalent is a pigmented gel coat moulded as the outer surface. A chip or a scratch in an integrally coloured panel exposes the same colour underneath, which is the property that distinguishes it from any applied coating.
Integral colour comes from the cement paste, not from the aggregate. That is why the same pigment at the same dosage produces a different result with white cement and with grey cement, and why changing the water content of a mix changes the colour of the panel.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Pigment dosage, cementitious | 1 to 6% by weight of cement | Above about 8% adds little colour and can weaken the mix |
| Principal pigment type | Synthetic iron oxide | Red, yellow, brown and black; fully lightfast in cement |
| Blue and green pigments | Cobalt aluminate and chromium oxide | Markedly more expensive per square metre |
| White pigment | Titanium dioxide, 2 to 5% by weight of cement | Used with white cement for pale shades |
| Base cement | White or off-white for pale and saturated colours | Grey cement dulls every colour and varies by batch |
| Gel coat pigment loading | Typically 3 to 8% by weight of resin | The FRP equivalent of integral colour |
| Effect on strength | Negligible at normal dosage | Excess pigment behaves as an inert fine filler |
| Colour tolerance | Assessed against an approved range of samples | State a delta E limit and a viewing distance |
How it works in a cementitious mix
Pigments for concrete are fine insoluble particles, typically under one micron, that coat cement grains and colour the hardened paste. They take no part in hydration. Because the colour belongs to the paste, anything that changes the paste changes the colour: the cement itself, the water to cement ratio, the proportion of paste to aggregate, the curing regime and the age of the panel all move the result.
Two consequences follow directly. First, a higher water content produces a lighter, patchier panel, because more capillary porosity scatters light differently, so batch water control is a colour control. Second, the surface treatment decides what is seen: an off-form face shows the paste and therefore the full pigment colour, while acid etching, sandblasting or polishing removes paste and exposes sand and aggregate, which mutes the pigment and shifts the colour towards the aggregate.
What controls consistency
- One cement source and one cement colour reserved for the whole job, ordered at the outset
- One sand and aggregate source, from a consistent pit face
- Pigment weighed rather than measured by volume, and preferably supplied as a pre-weighed dispersion or slurry
- Constant water to cement ratio, achieved with admixture rather than added water
- Constant mixing time and constant mix sequence
- Consistent demould age, curing temperature and humidity across the production run
- Panels assessed against an approved range of samples, not a single chip
The last point is the one that keeps projects out of dispute. Cementitious colour varies within a defined band even under good control, so the contract should establish a light and a dark limit sample, both approved, with production accepted anywhere between them at a stated viewing distance under daylight. The colour consistency entry covers the process.
Integral colour in composites and gypsum
In a fibre reinforced polymer panel, colour is carried in the gel coat, which is 400 to 800 microns thick and cast against the mould. It is integral to the panel in the sense that it is part of the moulding rather than a film applied afterwards, and it can be cut back and polished, but it is not colour through the full section. Deep damage will expose the laminate behind it.
Gypsum elements are usually painted rather than integrally coloured, because the paint finish on a GFRG panel is part of the interior scheme and the material is not exposed to weathering. Pigmented alpha gypsum is used where a chip should not show, though the colour range is limited compared with what a paint system offers.
Integral colour against a coating
Integral colour hides impact damage, chips and drilled fixings, because the colour goes through the section. It weathers evenly, since there is no film to fail, and it needs no recoating cycle. What it cannot do is be touched up: a patch repair to an integrally coloured cementitious panel will not match, because the repair material has a different paste, a different cure and a different age.
A coating is the reverse. A PVDF or powder coated finish holds a precise colour for decades under warranty, can be specified in any colour, and can eventually be recoated. It also chips to a different colour underneath, requires a maintenance regime, and on a cementitious panel it risks blistering where moisture or efflorescing salts arrive from behind the film.
Specifying it
Name the pigment type and the dosage as a percentage by weight of cement, the cement colour, the surface finish and the depth of etch or blast, since all four combine to make the colour. Require light and dark limit samples and a full size mock-up including a joint and a corner, approved on site in daylight. State the viewing distance and lighting for assessment, and require all cement and pigment for the job to be reserved from a single batch.
Set expectations about efflorescence in writing, particularly for dark colours, where a light bloom is far more visible. The efflorescence entry sets out the mechanism and the controls; the mock-up should be used to agree what a normal surface looks like after the first months of exposure.
Standards and references
- ASTM C979 Standard Specification for Pigments for Integrally Colored Concrete
- EN 12878 Pigments for the colouring of building materials based on cement or lime
- ASTM D2244 Calculation of Colour Tolerances and Colour Differences
- AS 3972 General purpose and blended cements
- National Precast Concrete Association Australia, Precast Concrete Handbook
- GRCA Specification for the Manufacture, Curing and Testing of GRC Products
Related terms
Questions specifiers ask
How much pigment is used in coloured concrete?
Typically 1 to 6 percent by weight of cement. Beyond about 8 percent the colour barely deepens and the extra fine material can reduce strength and increase water demand, so higher dosages are not a route to stronger colour.
Why do coloured panels vary between batches?
Because the colour is in the cement paste, and the paste changes with cement source, water content, mixing, curing and age. Reserving single sources, weighing pigment and holding the water to cement ratio constant are what control it.
Is integral colour better than painting?
It depends on the substrate. Integral colour hides chips, weathers evenly and needs no recoating, but cannot be touched up to match. A coating gives exact colour and can be recoated, but chips to a different colour and needs maintenance.
Can GRC be integrally coloured?
Yes. Pigment is batched into the mix in the same way as for precast, usually with white cement for pale or saturated colours. The same controls on cement source, water content and curing apply, and the finish treatment affects the result.
Does integral colour fade?
Synthetic iron oxides and the inorganic pigments used in cement are lightfast and do not fade. What changes over time is the surface: carbonation, weathering, dirt and efflorescence all alter appearance without altering the pigment.
Matching a colour across a whole elevation in a moulded cementitious panel? ShapeShell-RC is produced with integral colour and controlled from a single cement batch. See ShapeShell-RC specifications
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.