Nothing lasts forever! The color-changing effect can last for years, as long as the gloves are not exposed to acids, solvents or other harsh chemicals. Additionally, sunlight's UV rays will eventually overpower the ink and cause it to lose its color-changing effect. So please don't store the gloves in direct sunlight!Unfortunately there's no way to reverse the process once it loses its color-changing effect, and we're unable to replace gloves that have started to lose their effect (unless it was an obvious defect in manufacturing of course).