3M High Strength Color Changing Wall Repair goes on blue and dries white helping identify when a repaired surface is dry and ready to be sanded and painted. Eliminate the guesswork and reduces the chance of errors. It's ready-to-use formula dried quickly and provides professional-looking repairs.3M High Strength Color Changing Wall Repair goes on blue and dries white, helping identify when a repaired surface is dry and ready to be sanded and painted. Eliminates the guesswork and reduces the chance of errors. Its ready-to-use formula dries quickly and provides professional-looking repairs.