Sodium chloride, most commonly known as salt, is everywhere. Ancient in its uses and abundant in nature, it preserves local ecosystems, de-ices roads, is vital in a variety of industrial processes, and is likely sitting on your kitchen table as a seasoning for your meals. Today, it is attributed relatively little value –considering it used to be as worthy as gold–, and unlike other nature-derived alternatives such as algae or mycelium, there doesn’t seem to be enough research and interest around all of its physical, mechanical or aesthetic properties. And yet it is a material with infinite, extraordinary potential. Apart from its life-supporting qualities, salt is affordable, easily available, antibacterial, resistant to fire, can store humidity and heat, and is great at reflecting and diffusing light.
We know that one of the key challenges in improving resource efficiency in the building industry is to identify materials that can substitute rare natural resources, so could salt, with all its characteristics, become a viable option? Could it be a material of the future? Of course, just as there is potential, there are difficulties associated with salt that have limited its use as a building material: it is naturally prone to moisture absorption, susceptible to erosion by wind and water, and can cause corrosion to metal components used in construction. This implies that a long list of criteria must be met, but it also provides the opportunity to explore certain applications where salt could be beneficial despite the challenges.
Salt is essentially a chemical compound formed by sodium and chloride ions that, when dissolved in water, separate and become surrounded by water molecules. If the water evaporates, the ions come closer together and form a lattice structure that results in the formation of salt crystals. Crystals can form in a variety of ways, from the evaporation of seawater to underground mining and chemical reactions. As the world population grows and living standards improve, the amount of salt produced as waste through seawater desalination and potash mining has dramatically increased, meaning the resource is more abundant than ever.
To the surprise of many, researchers and designers have explored salt as a building material for centuries in some parts of the world, either in a raw, composite or processed form. Some interesting examples include a hotel built from millions of salt blocks, a restaurant made with locally-sourced salt, and an unbuilt pavilion in which metal frames were designed to encourage salt growth. New uses have also emerged over the last decade, from processed salt used in flexible wall panels and building skin prototypes, to 3D-printed objects made from salt and starch mixtures.
Crystallized salt panels that grow in a farm-like system
There is one design and research laboratory that has gone one step further, “using salt crystallization processes to develop innovative applications and strengthen the historic local salt industry.” Based in the vast Luma Arles campus in the south of France, Atelier Luma proposes a new, creative way to work with salt crystallization, unveiling the potential of a natural, circular process in the architecture and design field. We spoke with project manager Henna Burney to get more insight on the initiative and how it aims to position salt as a high-value material.
The saltwater of the Rhône river delta –or the so-called Camargue in Southern France– has historically been used to produce salt. Since 2017, Atelier Luma’s Crystallization Plant has focused on creating uses for the salt produced by the region’s salt makers, developing materials that feature this local resource and showcase its physical and aesthetic attributes. Using custom frames, the team produced the first series of crystallized salt panels that were grown locally using a farm-like system, taking advantage of the natural crystallization that occurs in the salt fields.
Designers Henna Burney and Karlijn Sibbel developed a way of growing the salt crystals “on a metal mesh placed underwater in the extensive salins.” In-depth research was necessary beforehand to determine how external conditions such as wind, rain, temperature, water flow and humidity would impact the crystallization process.
It is a natural material; in fact, we have not invented anything. We analyzed the crystallization process and what sort of crystallization we wanted, but the know-how belongs to the salt workers. – Atelier Luma on the ‘Wall of Salt’
Transforming salt into a material of architectural scale
For the salt panels, it was necessary to structure, delimitate and constrain the crystallization in a manageable geometry; in this case, a perfect square. Transforming a naturally abundant material into one of architectural scale, professionals were able to come up with a setup to produce more than 4000 unique panels that were then used as a glass-like cladding system for Frank Gehry’s tower at Luma Arles. Covering a surface of 560 square meters, the ‘Wall of Salt’ project represents the first large-scale application of salt as a cladding material.
As Henna explains, salt was chosen for the project “because it’s a naturally inflammable material. This was one of the requirements to be able to apply a natural material in that area.” And because crystallization involves a carbon-neutral process, the panels are also highly eco-friendly: “the production from solar energy (crystallization) doesn’t have any negative impact on the environment.” The structural design allows each individual panel to be removed and replaced when necessary; if damaged, these can be recrystallized and restored again by placing them back into the water of the Crystallization Plant. This way, with extensive research and following specific constraints, the salt panels proved to be an innovative solution capable of reducing heat loads, resisting fire, adding a unique aesthetic touch and contributing to sustainability.
What we set up is a particular farming method which enables us to create panels that can be used in buildings, which have real qualities in the architectural environment as they are fire resistant and enable a reduction in the heat load of a building. – Atelier Luma on the ‘Wall of Salt’
As Henna explains, one of the main motivations behind the Crystallization Plant is to “prove that it is possible to think about salt differently, using it as a material for architectural and design applications. But of course, as salt is a material that is part of the region, and the landscape that surrounds it hosts a biodiversity that actually depends on it, we wanted to propose a solution for preserving this landscape and know-how through the production of salt panels, using salt for more valuable applications.” Looking ahead, Atelier Luma continues to work on design applications that can take advantage of salt’s natural properties.
While there are many challenges to overcome to imagine a future where natural resources like salt will replace traditional materials, one thing is certain: “The future will be built with materials that are both new and old.” Hand in hand with research, new technologies and innovation, salt has the potential to be one of these new materials. After all, in order to truly improve sustainability and resource efficiency in the coming years, it is vital to draw inspiration from nature, support local production, and, most importantly, think outside the box and get creative.
