Urbanization in hot and humid regions such as southern China has increased the demand for comfortable indoor environments. In order to design a material for efficient passive indoor humidity regulation, this study investigates a composite material that combines the hygroscopic properties of salt and the adsorption capacity of diatomaceous earth (DE). Firstly, we prepared DE and boehmite into moisture-absorbing porous materials. Then, the initial DE-based sample was innovatively doped with SiO₂ nanomaterials and loaded with LiCl to enhance the humidity regulation ability of the composite, especially in the adsorption and desorption ability of water vapour. The microstructure and phase composition of the composite samples were analysed, and we observed an increase in porosity, filling performance and capillary condensation upon the introduction of SiO₂ nanoparticles. The hygroscopic salt loaded into the pores can absorb more water when exposed to the ambient humidity. This synergic effect can effectively improve the hygroscopic performance of the composite material while maintaining the stability of the physical and chemical properties. The optimized samples showed a moisture absorption rate of 28% in high-humidity environments, meeting moisture buffer value evaluation standards. The study’s findings lay the foundation for the future integration of these materials through advanced manufacturing technologies.

“A Grain of” is an art installation made by the authors: a small cube (25 x 25 x 25cm) of custom-made matter, sitting on a plinth, emitting sound from within. Its underlying idea is to take a “grain” from a dense, contemporary urban space and translate it into an art installation that makes the city experienceable for the audience. This small cube holds some of the material and sonic ecology of the city from which it stems embedded in it. In this paper, the authors describe the technical processes that they have used to sample and reinterpret the city’s material and sonic ecologies, including Atomic Force Microscopy (AFM), 3d printing, field recording, and sound synthesis. They offer some theoretical notes towards the grain of the city in order to investigate how this process of technical translation produces an experience with affective, poetic, and speculative potential. They argue that this experience lets its audience critically rethink the old enduring binaries between natural and artificial or between the city and nature.