Demi-permanent hair color is a type of hair dye that lasts longer than semi-permanent color but is less permanent than traditional permanent hair color. It typically lasts about 20 to 28 washes and is ideal for those looking to enhance their natural color or cover gray hair without the commitment of permanent dye. This formula contains no ammonia, making it gentler on the hair. The color molecules in demi-permanent hair color partially penetrate the hair shaft, allowing for a more subtle change. It often uses a low-volume developer, which helps to achieve a natural look while providing a boost of shine and depth to the hair.