Thermochromic dyes: Smart textiles: Heat Reactive Jacket by Stone Island, a tracksuit top which changes colour from black to green/ blue once it has reached 27 degrees. The fabric that is cotton nylon with thermosentive liquid crystals that react to heat.
The patterns on the umbrella are made of hydrochromatic ink which changes colour when rain falls. The black and white umbrella becomes colourful the moment it rains. Hydrochromic ink is a kind of water based ink, which can change colour from white colour to transparent when it gets wet,and would return back to original colour when it gets dry,hydrochromic ink can be applied through screen printing