What is string “pre stretching?
Pre stretching is a procedure that “takes up slack” in the string prior to or during stringing with the aim of achieving more tension stability over time. An old fashioned and rather inconvenient form of pre stretching involves tying one end of the string to a firm anchor and pulling on the other end (tug-of-war style) for a period of time. More sophisticated pre stretching is done during tensioning with constant pull machines. There is a number of ways of achieving pre stretching. One has to do with the speed at which the string is pulled to the reference tension: slow pulling results in more pre stretching. Another has to do with the length of time constant pull is exerted once the reference tension is achieved: the longer the string is pulled, the more pre stretching. A third form of pre stretching is achieved by sophisticated electric machines by exceeding the reference tension slightly before backing off to it.
