Natural Pigments in Architecture: Sources, Applications and Why to Use Them

In the face of a climate emergency, various fields are under pressure to reformulate their operations and actions, and architecture is no exception. After all, the built environment and the construction industry are responsible for a considerable percentage of carbon gas emissions into the atmosphere. Rethinking and restructuring the construction chain - from design to execution - is the order of the day for construction professionals.

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Amidst research, attempts, and questions about the construction industry's processes and materials, interesting and promising solutions are being developed or revisited. Turning to ancestral construction systems is not a recent attitude and was one of the theoretical strands of the 1960s. Observing and reclaiming some vernacular practices will certainly benefit contemporary architecture.

Architecture has much to teach before it becomes an expert art. Builders without tutelage in space and time - the protagonists of this show - demonstrate an admirable talent for adjusting their buildings to the natural environment. Instead of trying to "conquer" nature, as we do, they embrace the slowness of the climate and the challenge of topography. - Bernard Rudofsky

Taking it beyond sustainable building performance issues, architecture's constitutive "matter" must also be rethought. The construction materials must also be renewable, produced, transported, and disposed of with less environmental impact. Examples of enclosures are well-known: walls, and roofs. In terms of finishes, although the technique is familiar in historical records, there is no widespread dissemination of natural pigments and their use in construction.

Natural pigments have been widely used since ancient times for various purposes, including food coloring, paints, cosmetics, fabrics, and art. Making natural-based paint depends on two elements: a pigment and a binder. Pigments can be obtained from organic matter, such as saffron, annatto, onion skins, mashed beans, or vegetables. Binders (or mordants) ensure the adhesion of the dye to the surface and can also be organic, such as vinegar, salt, and yerba mate, among others.

Dyeing using natural pigments is more common in the textile industry. It has benefits: the variety of colors is not lacking, besides reducing the risk of allergies compared to chemical dyes. Industrialized paints require a lot of stabilizers and synthetic chemicals to ensure the vibrancy and durability of the color. These are mixed in water, where the fabric is soaked. Dyeing water is discharged into the city's infrastructure networks without being properly treated at the end of the process. Natural dyeing does not produce the same amount of waste. This makes it less harmful to the sewage system and eventually returns to the environment.

Construction follows the same. The pigment and the mordant are mixed with water and directly applied to the substrate. In general, the pigments are of mineral origin, such as clay, which results in a warm palette, from yellows to browns, depending on the type of soil. The most common binders tend not to be natural, due to the need for yield for a room or building. It is possible to use water-based white glue, whey (casein), or lime – which is also the basis for white paint.

Besides using it as a finishing paint, another alternative to coloring building materials is pigmented concrete. The pigment is added to a mixture of sand, fine and coarse aggregates – gravel, in general – cement, and water. Pigments do not influence concrete's structural performance and, unlike paints – in which the pigment is diluted in water – in pigmented concrete, the dye is mixed with the material and gives it color through mechanical dispersion. Due to the coloring process, pigments must be inorganic, such as iron oxide (reds and browns), chromium oxide (greens), iron hydroxide (yellows), cobalt oxide (blues), and titanium dioxide (white), all mineral based. To ensure their proper and sustainable use, it is essential to evaluate the extraction of these pigments. The performance, stability, and durability of these pigments in concrete guarantee the advantage over organic pigments. Their coloring capacity and durability do not meet this material's performance expectations.

Resistance to natural pigments is partly due to durability and color maintenance. Plant-derived pigments are photosensitive, meaning they change their hue, fade, and sometimes completely disappear when exposed to light for long periods. For this reason, a key part of developing and using these pigments is ensuring color lasts. In the case of mineral pigments, durability concerning the weather has a performance equivalent to industrial paints. This is an incentive for its diffusion in the civil construction industry. Can these pigments be industrially stabilized and potentiated responsibly?

It has been known for a long time that architecture is not eternal. Why would durability be an issue with natural pigments? They do not differ that much from the performance acquired “synthetically”, but they are undoubtedly less aggressive, and offer another way for the architectural field to exist in a more symbiotic and environmentally friendly way. The answer is always “no”. However, researchers, professors and professionals began to pair ancient techniques with modern scientific methods to prove that the answer can be changed to “yes”. Another aspect to be considered in the reformulation of constructive thinking is temporality (always the same). Maintenance of buildings happens regularly because of materials' wear and tear.

This article is part of the ArchDaily Topics: Color in Architecture presented by Sto.Material, texture, sheen, and color are inseparable – the identity of a building becomes clear in an Architect’s choices of how these come together. Considering the lifecycle of a building from design, occupation, and legacy, we understand that achieving the right expression is tantamount to the success of a building. Sto’s innovative materials and data-driven color system complement design ambitions with technical knowledge and rigorous testing, to offer possibilities, accuracy, and longevity when Building in Color.Produced by Sto, the short documentary ‘Building in Colour’ is a cinematic exploration into the role of materials and color in architecture, taking the work of Stirling Prize-winning architect Michael Wilford CBE (1938 – 2023) as its starting pointEvery month we explore a topic in-depth through articles, interviews, news, and architecture projects. We invite you to learn more about our ArchDaily Topics. And, as always, at ArchDaily we welcome the contributions of our readers; if you want to submit an article or project, contact us.

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