Playtest: Wilson Hollow Core 16
By Greg Raven
Hollow Core is an innovative nylon multifilament from Wilson. Hollow Core is the first string that, instead of a round solid core, has an air-filled, hollow triangle-shaped core. According to Wilson, this hollow core is what gives the string its unique playing properties, namely, superb power, comfort, and control. Around the triangular core are wrapped high-elasticity microfibers, which are coated for ease of installation.
Hollow Core is available in 16 gauge (1.33 mm) in natural only. It is priced from $9 for a 40-foot coil, and 660-foot reels go for $150. For more information or to order, contact Wilson at 773-714-6400, or visit wilson.com/newstring.
In the lab
The coil of Hollow Core 16 measured 40’. The diameter measured 1.32-1.34 mm prior to stringing, and 1.26-1.27 mm after stringing. We recorded a stringbed stiffness of 73 RDC units immediately after stringing at 60 pounds in a Wilson Pro Staff 6.1 95 (16×18 pattern) on a constant-pull machine.
After 24 hours (no playing), stringbed stiffness measured 63 RDC units, representing a 14 percent tension loss. Our control string, Prince Synthetic Gut Original Gold 16, measured 78 RDC units immediately after stringing and 71 RDC units after 24 hours, representing a 9 percent tension loss. Hollow Core added 15 grams to the weight of our unstrung frame.
The string was tested for five weeks by 35 USRSA playtesters, with NTRP ratings from 3.5 to 6.0. These are blind tests, with playtesters receiving unmarked strings in unmarked packages. Average number of hours playtested was 26.9.
Hollow Core feels soft out of the package, with a benign amount of coil memory. It is straightforward to install, with a smooth texture that glides through grommets and across the mains. It does, however, bruise easily in clamps and in the jaws of the tension head, even when using the nosecone.
No playtester broke his sample during stringing, one reported problems with coil memory, none reported problems tying knots, and none reported friction burn.
On the court
Our playtesters found Wilson Hollow Core 16 to be a great string across the board, rating it well above average in Playability, Control, Touch/Feel, Comfort, Spin Potential, and Tension Retention, with remarkable consistency in scores across all nine categories. On the strength of these ratings, Wilson Hollow Core 16 garnered a well-above-average overall ranking of the 130 strings that we’ve playtested for publication.
Three playtesters broke the sample during playtesting, one at six hours, one at eight hours, and one at 17 hours.
Given the ratings our playtesters gave Wilson Hollow Core, there’s little doubt that it can be the “go to” string for stringers with customers wanting a strong-performing string with no major drawbacks: There’s something in Hollow Core just about every player will appreciate.
Nearly a third of our playtesters commented that Hollow Core offered good power — one of the benefits Wilson claims for the technology behind this string — and most rated it accordingly. Most of the other playtesters who did not find Hollow Core particularly powerful still felt that it had the right power level in proportion with its playability, control, and touch.
“This is a nylon based string with the feel of natural gut. The response is crisp and clean. It has just right mix of power and touch.” 4.5 male all-court player using Head i.Prestige MP strung at 59 pounds LO (Gamma TNT2 16)
“Ease of installation is second to none. Great feel, especially around the net. I definitely notice added power on serves and groundies.” 6.0 male all-court player using Wilson K Blade strung at 53 pounds LO (Wilson Sensation 16)
“The playability is there from beginning to end. This is a great option for players with sensitive tendons. Durability is surprising for such a soft string. If you are looking to add a solid multifilament to your inventory, this is a very good choice.” 4.0 male baseliner with moderate spin using Head Prestige Classic strung at 62 pounds CP (Signum Pro Poly Plasma 17)
“This string is great for heavy topspin. It is very comfortable and makes a nice deep thud at impact. Power and spin come very easy.” 3.5 male all-court player using Volkl DNX 4 strung at 60 pounds CP (Wilson K Gut Pro 17)
“This string feels and plays like natural gut. It has great power without sacrificing control.” 4.0 male all-court player using Head MicroGEL Radical MP strung at 57 pounds LO (Gamma Live Wire XP 16)
“This string has a crisp feel and great spin. Tension maintenance is excellent. Control is remarkable and it does not diminish over time. This string is a ‘home run’ for players who like great feel, power, and comfort.” 5.0 male all-court player using Prince O3 Speedport Black (with port inserts) strung at 58 pounds CP (Luxilon Ace/Pro Supex Maxim Touch 18/16)
“This string has some serious power. The comfort and touch are there from the first hit.” 4.5 male all-court player using Babolat Pure Drive strung at 60 pounds CP (Gamma TNT2 16)
“This string has an amazing feel. The combination of comfort, spin, touch, and power is out of this world. Every shot feels just right. There is no adjustment period required. Controlling the ball’s depth and trajectory is extremely easy. The increased dwell time adds to the control.” 5.0 male all-court player using Dunlop Aerogel 2 Hundred strung at 58 pounds CP (Luxilon Alu Power Rough 16L)
“The combination of control, power, and playability makes this one of the best strings I’ve used in the last five years. In addition to being a great string for baseliners, it is exceptionally soft and extremely arm-friendly. Tension maintenance is good.” 4.0 male baseliner with heavy spin using Wilson K Blade Team strung at 52 pounds CP (Wilson Sensation 17)
“I threw the kitchen sink at this string. I did my best to break it. Yet, somehow, it feels fresh after 20 hours. This is a comfortable string with above average durability. It has a very crisp response, but without any shock to the arm.” 5.5 male serve-and-volley player using Wilson K Six.One Tour strung at 58 pounds LO (Gamma Dura Blast 16)
“This string has no huge negatives. It is crisp and clean from the baseline. Big swings can be taken without worry. I find myself targeting the lines and playing very aggressively. I don’t prefer nylon based strings, but this is one of the better ones I’ve tried.” 5.0 male all-court player using Volkl DNX 10 Midplus strung at 62 pounds CP (Luxilon Alu Power Rough 16L)
“As an occasional victim of tennis elbow, I prefer soft strings with good control. I’ve played with too many multifilaments that get mushy after 3 hours. This string does not lose control or feel until well after the 10-hour mark. The ball stays on the strings seemingly forever. I’m considering a switch.” 4.5 male all-court player using Wilson H Tour strung at 58 pounds CP (Head Intellistring 16)
“I’ve been searching for a comfortable string with good bite and above average tension maintenance. I think I’ve found it!” 3.5 male all-court player using Slazenger NX 111 strung at 62 pounds LO (Gamma Asterisk 16)
“Great feel. The low power level makes this a control string. I feel very unconstrained from the baseline. No matter how hard I swing, the ball goes in.” 4.0 male baseliner with moderate spin using Head Metallix 2 strung at 56 pounds CP (Wilson NXT 16)
“Very comfortable string. It has a very cushioned feel. Very responsive and lively on serves and volleys. Durability might be an issue for big hitters.” 4.5 male all-court player using Wilson K Pro Open strung at 58/61 pounds LO (Prince Pro Blend 16)
“This string allows one to hit deep, penetrating shots. It is not only comfortable, but it has good control and great pop on volleys. There is some string movement, but I remain impressed with the extra spin on serves and groundies.” 4.5 male all-court player using Prince O3 Speedport Black (with port inserts) strung at 55 pounds CP (Luxilon Alu Power 16L)
“This string has outstanding playability and comfort. After some tension loss, the playability goes down.” 5.0 male all-court player using Head Liquidmetal Prestige Mid strung at 58 pounds LO (Prince Synthetic Gut Original 16)
“This string has a wonderfully comfortable and powerful response. It is recommended to players who prefer a soft feel. The power is very easy to control. The strings tend to move on topspin shots, but not excessively.” 4.5 male all-court player using Volkl DNX 1 w/Power Arm strung at 57 pounds LO (Forten Dynamix 16)
“This is a very easy string to install. The crosses glide very quickly. There is no string movement. Tension maintenance is above average. Even after 20 hours, this string looks fresh and plays lively.” 4.0 male all-court player using Prince O3 Blue strung at 56 pounds LO (Gamma Live Wire Pro 17)
“This is a low powered multifilament with good control.” 4.0 male all-court player using Volkl C10 Pro strung at 55 pounds LO (Babolat VS Team 17)
“Not only is this is a soft and comfortable teaching string, it is crisp enough for competitive play. It could be classified as a comfortable control string. After losing tension, it gets a little mushy.” 5.0 male baseliner with heavy spin using Wilson K Six.One (76 Holes) strung at 56 pounds LO (Polyester/Nylon 16/17)
“This string has good overall performance. The tension maintenance is impressive. At 63 lbs, it feels a bit ‘boardy,’ especially for teaching. It does not seem to lose crispness or get softer over time.” 4.5 male baseliner with heavy spin using Wilson nPro strung at 63 pounds LO (Head FXP Power 16)
“This is a comfortable string. There is some moderate notching. It has good spin and playability.” 4.0 male baseliner with heavy spin using Tecnifibre T Fight 315 strung at 58 pounds CP (Signum Pro Poly Plasma 18)
“This string handles 30 hours of intense play without noticeable tension loss. It has tremendous power and accuracy. There is definitely a little string movement.” 4.5 male serve-and-volley player using Wilson Hyper Hammer 2.3 Stretch OS strung at 60 pounds LO (Wilson Sensation 17)
“This string has a very soft composition. Installation is painless. It is very comfortable, but over time it loses pop.” 5.0 male all-court player using Head MicroGEL Prestige MP strung at 60 pounds CP (Nylon Multifilament 17)
“Control is adequate, but the feel is a bit harsh.” 4.5 male all-court player using Prince OZone Pro Tour MP strung at 57 pounds LO (Prince Synthetic Gut w/Duraflex 16)
“The feel is great, but it goes dead after a few hours of heavy hitting. It might be a bit too soft for players who prefer a stiff response. This is an excellent offering for recreational players. It would also be a great choice for those with “tennis elbow.”” 3.5 female baseliner with heavy spin using Babolat Aero Strike strung at 58 pounds CP (Prince Tournament Poly/Prince Synthetic Gut w/Duraflex 17/16)
“Installation is very quick. String movement is minimal, and tension maintenance is truly impressive. Even so, it’s hard to categorize this string. It has the stiff feel of a poly, but lacks the powerful ‘snap-back.’ Given its low power level, it is recommended to those who make their own power.” 5.0 male serve-and-volley player using Wilson K Blade strung at 55 pounds LO (Wilson Enduro Pro/Wilson Sensation 17/16)
“This is a crisp string with moderate spin and power. The durability is lacking.” 3.5 male all-court player using Yonex RQIS 1 Tour strung at 60 pounds CP (Ashaway Crossfire 18)
“This string lacks the ‘wow factor.’ It plays like a ‘middle of the road’ nylon multifilament.” 5.0 male all-court player using Head MicroGEL Extreme strung at 58 pounds CP (Polyester/Natural Gut 18/16)
“This string is quite noisy. The tension maintenance is excellent. The spin potential and control are on the low side.” 5.0 male baseliner with heavy spin using Prince O3 Speedport Black (with port inserts) strung at d62 pounds LO (Prince Tournament Poly 17)
“Very easy installation. There is some ‘clouding.’ This string plays like a solid-core nylon. The comfort level is high. Power and spin are below average. This might be a good alternative for polyester users who like control, but want a softer feel.” 4.0 male all-court player using Volkl V1 Classic strung at 58 pounds (Babolat VS Team 17)
“This is a very durable multifilament. Great spin potential, but lacking touch and feel.” 4.0 male all-court player using Avery M3 Control strung at 60 pounds CP (Gosen Polylon 17)
“Surprisingly crisp for a string with such high shock absorption. Tension seems to drop precipitously after 15 hours (which isn’t bad for a nylon multifilament). As usual, I do not have much luck generating heavy spin with non-polyester strings.” 4.0 male baseliner with heavy spin using Babolat Pure Drive strung at 58 pounds LO (Polyester 17)
“This string feels like a very thick gauge. The comfort level is not as high as one would expect for a multifilament. The lack of feel causes control problems.” 4.5 male all-court player using Head MicroGEL Radical MP strung at 51 pounds CP (Head UltraTour 16L)
(Strings normally used by testers are indicated in parentheses.)
|EASE OF STRINGING
(compared to other strings)
|Number of testers who said it was:|
|about as easy||16|
|not quite as easy||1|
|not nearly as easy||0|
(compared to string played most often)
|Number of testers who said it was:|
|about as playable||13|
|not quite as playable||10|
|not nearly as playable||2|
(compared to other strings of similar gauge)
|Number of testers who said it was:|
|about as durable||22|
|not quite as durable||7|
|not nearly as durable||1|
|From 1 to 5 (best)|
|Resistance to Movement||3.3|
See all articles by Greg Raven
About the Author
Greg Raven is an associate editor for RSI magazine and technical writer. He is certified as a Master Racquet Technician by the U.S. Racquet Stringers Association. He can be reached via e-mail at email@example.com, or through Facebook, LinkedIn, and Twitter. He plays tennis five days a week, and is turning into an avid cyclist.