Tong Lin and colleagues at the Australian Future Fibres Research and Innovation Centre at Deakin University wanted to use layer-by-layer (LbL) deposition to form a stable coating of silica nanoparticles. The method alternates positively and negatively charged layers of a material. Previous research has used LbL for sensors and other devices, but the deposition process can be unstable, breaking down in acidic or alkaline environments. To stabilize their compound, Lin and colleagues blasted it with ultraviolet radiation. This anchors the nanoparticles onto the cotton fabric. The method can work with almost any organic substrate, they say. So that means things like wool, coconut or hemp clothing could be waterproofed, too.