Color-changing T-shirts utilize thermochromic or photochromic inks that react to temperature changes or UV rays, respectively. To activate the color change indoors, specific methods are necessary.
For thermochromic inks, heat activation is required. Holding a warm object near the design or using a hair dryer on a low heat setting can initiate the color change. Alternatively, placing the T-shirt in a warm environment, such as near a radiator, can also activate the effect.
