Originally Posted by julianashaway
Thank you, Torres, for the in depth explanation. The decrease in the ability to impart spin on the ball is an interesrting observation. String movement or tension loss would be an easy explanation. Since you are not experiencing either, my best guess (and this is just a guess) is a change in the integrety of the string surface itself from repeated contact. Are you a heavy top-spin player? It is unlikely that you would be able to see any change in the appearance of the string (I'm sure you would have reported it if you did). As you know, Monogut ZX is a very smooth string. Also, Zyex has a higher friction coefficient than poly, which makes it more susceptable to nicks and scrapes - one of the reasons for the detailed strining instructions we provide. I am wondering if this susceptability to friction is affecting the surface as you play and changing your ability to control spin. Of course, it could be something completely different.
Do you have access to a microscope or magnifing glass? If you do, I would recommend looking at the string from your hitting zone magnified and compare to the same magnification of unused Monogut ZX or some from the outer areas of the racket where your don't make much contact. Just an idea.
Interesting hypothesis Julian. From various descriptions of Zyex that I've found it sounds like it is, as a material, quite abrasion resistant. Do you think, though, that it is not quite as good as a slippery copoly in this respect?
If your hypothesis of surface scuffing were on target, it would seem that pairing it with natural gut mains would be boon, as TW University testing has show that gut mains with crosses that are at all slippery results in a pairing with lower coefficient of friction than either string strung as a full bed.
Also, would you care to weigh in on the widespread theory that loss of elasticity or resilience is responsible for the perception that a string, particularly a poly, has "gone dead"? TW University tests for tension loss, dynamic stiffness and energy return, all of which seem to converge around "elasticity" but none of which define it. In physics terms, I believe elasticity is defined as the slope of the stress/strain curve. So a loss of elasticity would seem to be a change in the shape of that curve and I haven't seen any studies that have attempted to document such a change. So at this point it seems difficult to objectively evaluate claims that a string has lost elasticity along with lost tension. Has Ashaway quantified elasticity and elasticity loss?
Torres reports that his strings have not lost tension, but I'm not sure if he's established that objectively with a stringbed stiffness measuring device. It seems, given your earlier statement about ZX not changing in stiffness much as it loses tension, that it may feel as though it has not lost tension but in reality could have done. With a poly string, by contrast, the dynamic stiffness drops off in proportion to tension loss, so it's quite easy to tell when strings have elongated as a result of repeated impacts or the passage of time.