While much have been said about how heat causes tension loss in synthetic gut, I have not read nor heard much about how heat affects poly strings.
So I did a simple experiment comparing poly with synthetic gut...
Objectives
(1) To test effect of heat on string tension, and
(2) To test effect of impact stress on string tension.
Methodology
- A piece each of new synthetic gut and poly string was manually pre-stretched for 120 seconds, then tensioned thrice at 50 lbs in the 6th and 7th main in a tennis racket, then tied-off.
- The pre-stretching and triple tensioning was to reduce tension loss through string relaxation.
- Tie-off tension loss would be very significant but not of interest in this study.
- Each impact stress was simulated by using a ruler to measure and depress each string about 1 cm deep, thrice.
- Note that when each piece (ie 6th main or 7th main) of the same string type is depressed, sometimes the tension differential would change between these two string. So the average is taken for greater accuracy.
- For heat stress, a hairdryer was held 1 cm away from the strings and moved slowly along the string for a total of 1 minute each time. The temperature was constant at about 40 degrees Celsius, which was well below the temperature in a parked car in the sun. (link1)(link2)(link3)
- All tension loss measurements were done through string frequency in Hertz (Hz).
Findings
Remember, the strings were both heavily pre-stretched and tensioned thrice. Despite that, what stood out was, from the total tension loss:
(1) poly lost less through string relaxation compared to syn gut,
(2) syn gut lost almost nothing through impact stress whereas poly suffered badly,
(3) heat affects syn gut twice as badly as poly, and
(4) as long as kept away from heat, syn gut's tension holding is impeccable whereas poly must be restrung very often for hard-hitters.
From my previous 10 full syn gut and 10 full poly string jobs, I felt the strings became unplayable (dead, harsh, no spin, poor control, etc), when the tension loss (in hz) reached about 9% for syn gut and about 6% for poly.
Based on the above, poly became unplayable to me after the 1st impact stress. Syn gut "died" after 2 mere minutes of heat stress.
Keep strung rackets away from heat if possible and restring poly very very often.
Natural gut always attract a lot of interest and attention. It is a pricey string, but it also plays second to none.
As soon as I posted my second "pilgrimage" (link), I received a barrage of questions on how the setup plays, how long it lasts, is tension holding really that amazing, how much it costs, etc.
To save myself from becoming a broken record, I compiled some observations in this post.
Stringing
- Before opening the pack of natural gut, every grommet hole must be carefully inspected for sharp edges. Any found must be gently and smoothly sanded down. Then checked again.
- New grommets or new unstrung rackets should not have natural gut as their first stringjobs.
- Gut kinks easily. Previously, I accidentally dropped the gut after snipping off the cable tie and the entire 40 ft tangled up in a huge mess! (link). A light prestretch is a must. Not optional.
- After the prestretch, I always inspect the gut for any kinks or bad patches before stringing. If found, photos were taken and sent to the owners to decide if they want to proceed at their risk.
- To prevent friction burns, either with the grommets or the crosses, waxing is a must. I do it twice - before and after stringing.
- All clamps, including the string gripper, should be cleaned and adjusted before stringing. Too tight and the gut flattens or snaps. Too loose and it slips.
Playing
- Some claimed gut needed a break-in period. Mine played well from the first hit.
- Gut/poly was very lively, crisp and pocketed the ball very well. The string rebound was fast and powerful. The long dwell time allowed me to execute a lot of strokes I usually could not. Even late hits or last minute saves sometimes became offensive shots!
- Spin was very easy and serves were effortless. Mid-game, when I swapped back to my full syn gut for a test, I had to swing so much harder for my serves. And I lost a lot of control and double-faulted!
- Visually, my partners and I noticed my ball speed was much slower with syn gut. They could chase and return what would have been winning passing shots with natural gut.
- Comfort was supreme! The ball must have enjoyed the hits! It probably felt more like landing on a plush pillow than being bashed by a tight stringbed.
- Even with the small 85 square inch frame, I felt gut/poly opened up the sweetspot larger than on a 100 square inch frame with other strings. It inspired confidence to just let go and rip the ball back. And most times, it turned out perfectly, just like on TV! So much so, that at times, I believed I could execute some of those shots-of-the-day by the touring pros.
- Instantly, just by using gut/poly, it gave me about a 30% improvement in my overall game.
Tension Holding
- Tension stability was impressive. Nothing comes close.
- Stringbed frequency measurements below:
| Total Usage (hours) |
Frequency (Hz) |
|---|
Strung
|
659.0
|
1.5
|
648.0
|
3.0
|
643.8
|
4.0
|
640.9
|
6.0
|
639.3
|
8.0
|
637.0
|
- As a comparison, most other strings usually drop about 30 to 40 Hz overnight after stringing without play. This setup lost only 22 Hz after 8 hours of play.
- Playing conditions (in Singapore) for the 8 hours was in the low 30s degrees Celcius. New pressurized balls were used, sometimes new Wilson trainers.
- Being excited with the setup, I stood slightly further back from the baseline than usual and swung much more freely than with my usual syn gut. In other words, I bashed the ball much harder than usual.
Poly String Death
- Since I restring myself, and none of my strings were used beyond 10 hours, I am very sensitive to flat strings.
- Somewhere around the 4th or 5th hour of use, I started struggling with this stringbed. Initially, I thought I was not performing well that session. Felt sluggish, lacked power and sprayed some shots wide. I stepped up and swung harder.
- Then, the tennis balls felt a little flat. So I changed to new balls. Immediately, control dipped. Shots flew long.
- The rebound timing of the stringbed was off. When fresh, the ball pocketed deep, then came off the strings enthusiastically, powerfully. Now it felt tired. It pocketed, but returned much slower and weaker. This longer dwell time meant a later part of my follow-through was now determining the ball trajectory.
- By the 5th session of use, which was going into its 7th and 8th hour, the sweetspot almost completely disappeared. Most of my impacts felt more like framed-shots with some light string buzzing.
- My serve lost so much pace and control. Volleys were so weak the ball kept dropping into my side of the net.
- The racket became very difficult to use and dragged me down. Shots that previously could be pulled off all fell flat.
- For the first time, the kevlar/graphite composite PS6.0 felt stiff with jarring vibrations! Both my wrist and elbow felt very uncomfortable too.
- As a simple test of resiliency, I pulled several gut mains apart and released. All snapped back very quickly. Pulling the poly crosses aside was so much easier. Less strength was needed and less resistance encountered. Not a single cross string snapped back when released. (See crosses 3 to 11 above, all pulled aside)
- Clearly, the gut was still behaving very well, and was supporting the bulk of the ball impact. However, the huge tension loss in the poly created too much "slack" for it to be of any further use.
Replacing Only the Crosses
- The beauty of a gut/poly hybrid is, you can restring ONLY the dead poly!!! (If your stringer would not do it, find another who would!)
- Beware! Hybriding poly with gut WILL NOT insure you against wrist pain nor tennis elbow. Mine hurt after merely 6 hours of use. The poly "died". Use poly safely. Always replace them after 8 to 10 hours, or less.
- While removing the cut poly strings, a sharp edge caught on the gut and snapped the 7th main. Fortunately, the tension loss was contained within the top 2 and bottom 2 crosses due to the way I had strung earlier (link).
- I clamped the 4th main on both sides, re-worked and re-tensioned only the 5th and 6th main strings. Thus converted the gut to fill only the centre 12 mains. The centre 8 mains were completely untouched from its initial stringjob.
- I smeared some coconut oil on the gut strings to lubricate it. Then filled all the rest with synthetic gut and saved a snapped gut string job!
Playtest
- The stringbed came to life again!
- All the earlier felt components - power, control and comfort came back in full force! Only spin was slightly less than before.
- At my first session after this re-work, my partner, "F", commented via a sms message after our game:
"Actually today your shots were pretty accurate, percentage higher than all other times. Strings or skill?!"
- It had to be the natural gut! How could I improve so fast?
Most pros like fresh stringbeds that are usually less than a day old.
Amateurs have varied preferences. Some like them straight off the machine, while others like to leave their new stringjobs at least overnight before playing.
But how long would an unused stringbed stay fresh?
I have tested the daily frequency changes of several freshly strung syn guts over a week. Unused, the greatest drop always occur in the first 24 hours.
Depending on the initial tension, string pattern (ie 16x19 or 18x20), gauge, etc, about 6-8% (by frequency) was lost in the first 24 hours.
Then over the next 72 hours, another 3-5% would be lost, but at a much more gradual pace. On average, total loss would add up to about 10-12% before play.
After this "rest", when play commenced, tension loss was very gradual. Each session saw a drop of only about 1-2%.
When a fresh stringbed was allowed to "rest" overnight, the tension loss after the first session of play was reduced by about half. The other half was lost when unused. This total loss amounted to about 8-10% by frequency.
When "rest" was not given, and it was played as soon as possible after it was strung, it lost about 8-12%.
From these, it appears the initial tension of about 10% (+/- 2%) could not be avoided. It's just a matter of letting it drop before or during play, whichever one prefers.
Out of curiousity (or boredom, or madness), I replaced my guitar's "G" string with a length of new syn gut. It's the black string third from the right in the pic below. The original "G" string lays on top.
It was tuned to 196.00 Hz. (link)
Over the next 24 hours, I re-tuned it multiple times back to 196.00 Hz. By the third day, it almost stabilized.
Then I replaced the syn gut with another fresh piece, tuned to 196.00 Hz and left it untouched. After 24 hours, the frequency dropped almost 9%. After 48 hours, about 10%. Then I re-tuned it. The loss over the next few days was insignificant, but it required re-tuning nevertheless.
So?
I think it is acceptable to re-string with full syn gut and leave it for a while before playing. The tension loss is definitely not a straight line down. It will plateau.
And, the syn gut sounded horrible on the guitar!!! On the other hand, natural gut was extremely and addictively melodious!
For many months, I've been relying on the frequency based method of measuring string tension loss.
As an absolute measure of what tension the stringbed is at, I think it fares badly. However, when used as a relative measure to check how much tension loss accumulated after play, I think it would be second to none.
I usually re-string after about 8-10 hours of play, or when the strings feel sluggish and lifeless to me.
Then, I became curious if this deterioration could be measured. So I started pinging the strings before and after every session of play and tracked a few rackets for several months.
Indeed, there seemed to be a correlation! The simple tension loss graph below shows it best. (Click on it to see a larger version)
Both the red and magenta line denotes tension loss from synthetic gut. The blue line tracks tension loss from a poly/syn gut hybrid.
I was careful to ensure the same spot was pinged for the frequency measurement. Strings that moved out of alignment during play were also straightened before pinging. Dampeners were removed.
The gaps were due to different number of hours played each session so it can be ignored. Just connect the dots.
The most significant observations to me were:
(1) a high initial tension loss during first hour of play,
(2) bottoming out of tension loss around the 6-7th hour.
From this, I'd like to think that I have a sensitive enough hand and a consistent enough sweetspot contact to pick up the gradual "tightening" after the 6th or 7th hour of play. To me, that was a sign that the strings were "dying".
While I did not add another observation to the chart, but I did notice in another few rackets that I strung with the aircon on, suffered almost twice as much initial tension loss (in hz) compared to those above.
Stringing in an aircon or cold environment increased the rate of initial tension loss, especially when my normal playing temperature is in the 30+ degrees celcius.
Anyone game to try asking their stringer to string their rackets under the sun?
A reader of this blog named "F" contacted me regarding my post on stringing machines (link).
F was totally intrigued by what I claimed to be significant differences in playability between stringing machines. He wanted the truth and suggested a "Myth Busters" experiment at his expense.
The plan was simple. He owns several matched rackets. He will get one strung by someone with an electronic machine and one on my dropweight.
To prevent any string biasness, he bought three packets of the same synthetic gut from the commercial stringer. One was used to string his racket electronically.
The second pack was given to me to string his other racket at the same tension and same stringing pattern (ie. 2 piece with exact tie-off holes)
After measuring the tension (by frequencies) of both stringbeds, we proceeded to hit some balls at the tennis court. Three of F's tennis partners (about ntrp 5.0 players) joined us and played with the unmarked rackets. Each had exactly 5 minutes. Only F and me knew the differences. The others were kept totally in the dark.
Unanimously, all expressed a strong preference for the dropweight strung racket. The three friends even thought the electronically strung racket had dead, old and stale strings!!!
The differences all of us felt most significant were:
1. stringbed liveliness,
2. power, and
3. spin
String tension was measured after every 30 minutes of play for 2 hours. After the session, the strings were cut out, preserving several long continuous pieces intact from the same spot in both rackets. Specifically, the centre 6 mains and between crosses 6-12.
Elasticity of the four lengths of strings were tested by holding them under tension at 50 lbs in the dropweight.
Here's our findings:
Initial String Tension
- The electronically strung racket registered a frequency about 58hz higher, translating to about 6 lbs tighter.
After Play String Tension
- At 30, 60, 90 and 120 minutes of continuous play, the dropweight strung racket (orange line) lost much less tension than the other racket (blue line). The rate of tension loss also stabilized after about an hour whereas the electronically strung continued losing tension even at 120 minutes of play.
Elasticity Test
- Both pieces from the electronically strung racket lost a lot more elasticity.
- Both dropweight strung pieces of string stretched about 2.3% more than the other string.
- The full stretch was recovered when tension was released for all the strings.
As far as F and his partners are concerned, they have found their answers.
Note:
Since this test could affect someone's livelihood, no details nor pictures were posted. Neither would any questions concerning the racket, string brand or electronic machine be answered.
