Shruthi Ramakrishna, Co-Founder at Made in Earth, an architecture studio based in Bangalore, writes about infinite colour and texture options that natural plasters offer
At every step in history, Earth as a building material, has rendered itself in response to the challenges of that time and to the aspirations of people. Earth proposes incredible options for an architecture that is concerned with the environment friendliness of the entire building process; of which materials play a substantial role. More and more contemporary architects are using materials that have as little processing as possible, such as earth, lime, wood, straw and bamboo.
Today, Earth architecture has developed in an extraordinary variety of forms, in an astonishing diversity of architectural languages which eloquently express the social, environmental, geographic, climatic and cultural aspirations of the people. We have several examples of airports, embassies, hospitals, museums, factories and homes all over the world that are made in earth.
One of the most simple and ingenious ways of bringing earth into our homes is by using natural plasters. Have you ever wondered why the feeling of comfort is different, between one room to another in the same building, even when the air temperature is similar? This is because temperature is only one of the many aspects which affect our feeling of comfort. The amount of humidity in the air, air movement, the exposure of walls to the weather conditions outside, the colours and textures of the internal wall finishes and the physical properties of the materials around you are other very important parameters in the design of our interiors.
The role of wall plasters in buildings today tends to be limited to protection of the walls and to providing a flat surface. Both colour and texture is addressed through chemical paints that one would apply above the plaster. Walls represent an average of 50 percent of the surface area in contact with our interiors and their role on our comfort is very important. Bringing natural plasters back in our homes opens a new world of possibilities which can greatly improve our well-being while offering unlimited options for aesthetics.
Natural plasters and finishes are made mostly of materials directly available in nature and which require little or no energy for their processing. They are therefore more healthy and eco-friendly. They can be categorised in two families: lime based finishes and clay based finishes. Lime and clay are both binders; they can be considered as the flesh of plasters; holding the rest of the materials together. Sand, quarry dust, recycled building materials or natural fibres are mixed with them in different proportions to give a structure or a skeleton to the plaster.
Lime is obtained by firing limestone. It is a traditional material produced all around rural India and can be used as a replacement of cement to obtain water proof plasters, suitable for exterior walls. Lime based finishes are also suitable for internal spaces that are humid, such as kitchens and bathrooms. Clay is the smallest particle in the composition of soil which, when in contact with water, becomes malleable and can be mixed with other materials like sand or fibres. It has an extremely high binding capacity and is ideal for interior plasters.
The materials that we use for our interiors have a big impact on the quality of the air that we breathe. Lots of the current industrial materials such as paints, varnishes, glue, etc release volatile organic compounds (VOC) in the spaces that we live in and continuous exposure to these chemicals have respiratory effects on us, and most certainly, on the people involved in construction of the building.
The use of natural paints and plasters eliminates exposure to VOC and in fact has a positive impact on the air since they help in the regulation of humidity and temperature.
The possibility of adding natural fibres in the plaster mix can also help in thermal comfort of our homes, especially in hot and dry climates. The fibres in the plaster mix act as insulation, depending on the proportions in which they are used.
Our buildings need to breathe! Human activities generate a lot of humidity (cooking, bathing, breathing, sweating) which needs to be evacuated. Generally this is done through mechanised ventilation (exhaust fans) or natural ventilation (ventilators or windows, when the climate allows it). However, in the case of high moisture content in the air, for example while taking a hot water shower or during monsoon, one will still experience some discomfort: such as condensation on the mirrors and walls, appearance of mould on the walls, peeling of paints etc. Clay based plasters have the natural ability to absorb this excess of humidity in the air and release it slowly.
The principle virtue of earth as a building material lies in its aesthetics, one that is natural, subtle and simple, adapting itself to the diversity of techniques, cultural aspirations and skills; sometimes in response to tradition, while sometimes contemporary. Working with natural plasters allows one to play with a lot of different textures and colours. Eliminating the need for a chemical paint over it, natural plaster renders can be sponge finished, smooth or trowel finished, rough or brush finished, hand finished, fibrous, plain, grainy, and together with natural colour pigments, the options are infinite.
Communities all around the world, have developed their own natural plaster recipes, using the materials locally available to create unique finishes. Lime-based plasters from Chettinad and Rajasthan in India, rice husk and clay based plasters from Japan, and natural soap based finishes from Morocco are an immense source of inspiration for our contemporary interiors.
The aesthetic also comes from the beauty of its imperfection. No two plasters or finishes are the same, the craftsmanship will express in the minute variations of texture and colours created by the movement of the hand, the strokes of the tools and the time taken to render the finish. This touch makes it unique and inimitable. The appreciation of this aesthetic is essential if one were to move away from the aseptic, standardised monotony of industry produced paints. When applied with imagination and in the right context, natural plasters can change the meaning of wall finishes as we understand it today. Natural plasters can not only give your space an earthy handmade touch, but also bring in a sense of timelessness.