When shading and tattooing in general, the tattoo needle sticks out of the end of the tattoo machine about 2 millimeters. If the tattoo needle is shorter than 1 millimeter, it may not penetrate the skin to the dermis, where tattoo ink should be injected.
If the tattoo needle is not extended far enough from the machine, the ink is put into the epidermis, where it bleeds out and fades as the tattoo heals. The tattoo needle is extended too far if the skin starts to bleed profusely during the tattoo. When correcting the length of the tattoo needle, the tip of the needle is adjusted.