Pre-stretch or not?
Some stringers like to pre-stretch the string before or during installation. This is strictly a personal preference of the stringer or the player may request it. If you decide to make pre-stretching a part of your preference, we recommend that you be consistent and do it on every job using the same method. But before you decide to do that, ask yourself WHY?
Pre-stretching was a common practice decades ago when the majority of strings on the market were natural gut. That is certainly no longer the case and now with monofilament co-poly strings being so prominent many feel that pre-stretching is no longer useful. It is purely up to the individual. To make a sound decision, you must ask yourself WHY? Why are you pre-stretching? Does it add any value or advantage to your service or gameplay?
The stringer approach
Pre-stretching basically elongates the string prior to installation so it takes some of the resiliency out of the string. Another advantage can be relieving some the coil memory by relaxing the string making it easier to handle during stringing. You have to determine whether pre-stretching provides any value.
Most electronic stringing machines have a "pre-stretch" function that can be set in either lbs./kgs. or a percentage. This function simply has the machine over tension the string pull to the set pre-stretch amount and then relaxes back to the set tension. Using machine pre-stretch would help to make up the tension deficiency of the string end that is furthest away from the tension head to be closer to the set tension and for string installers who does not handle the cross strings well due to technique deficiency.
The player approach
Pre-stretching will result in a tighter stringbed stiffness and slightly less initial tension loss because the string will stretch less during stringing because it has already been stretched. Many believe that it also makes the string feel stiffer since some of the elasticity is stretched out.
To conclude
While some stringers pre-stretch all strings, many save the practice for softer, more elastic strings such as multifilament and natural gut. One side effect is that it does relax some of the coil memory of the string resulting in easier handling. Regardless of the approach that one would take, consistency is the key.