The finger
Release the fingers and swing the i finger to the string. The finger swings on a hinge (the first knuckle) and goes to the string. The finger lands directly on the nail and flesh at the same time. By landing on the nail, a "ticking" sound is avoided. Further, the nail lands on the side of the nail, not flat on the nail, but at an angle to the string. The nail then crosses the string in exactly one point on the string and on the nail, avoiding the sound of "wiping" the string with the nail. Once the finger is on the string, landing on the nail, the finger pushes (not pulls), the tip joint releases, and a clean 'snap' occurs, without ticking or wiping sounds.