I wear safety glasses when working with watch mainsprings but wear a full face shield and leather gloves when doing clock mainsprings. I had one shatter about 10 yrs ago while winding it to put it in a barrel of a old German clock. It shattered and put 4 stitches right below my ear and 7 in my thumb. When they shatter the edges are like razor blades. Not trying to be a alarmist or what have you. Just saying be safe.
