The Core of Modern Golf Balls

When we were kids, before we knew what golf balls were really for, much delight could be gathered with an old Titleist and a hacksaw. (Go ahead; deny it if you can.)

Gee, those windings seemed to go on forever, didnt they? And in the middle, there was the core, sometimes liquid-filled. You could see, stretch, and bounce the physical evidence that these things could really zip off a clubface.

Fast-forward 35 years to my own garage, where I have put the hacksaw out of reach of anyone under six feet tall. That wont keep my son away from golf ball surgery forever, though, as he insists on getting taller and more resourceful.

But what will the second generation of Barr golf-ball cutters find? Not the wound technology of just a decade ago, but a huge, super-ball-like rubber core encased in an impossibly thin, durable cover.

Thats the modern golf ball. Even when you get past the dimples and open them to the world, todays balls have no visible technology such as windings and a liquid center. Instead, there is a uniform orb of polybutadiene (mostly) that bounces and flies better than anything the industry has yet devised.

Why?

Theres been a capability of generating high ball speed for years, but not necessarily at a low compression rate, says Steve Ogg, senior director of product customization for Callaway Golf. The old high-speed balls were hard balls that spun too much off the driver. Now, low core compressions keep the spin rate down off the driver.

Rubber cores have been around ever since the Molitor, says Mike Pai, vice president of marketing for Srixon, the golf arm of a huge Japanese rubber company. The elasticity of the material itself, weve been able to improve. The solid rubber core of today compared to one of 15 or 20 years ago is much better. Its being able to work with different chemicals and additives.

Ah, now were getting somewhere. Better rubber, better additives, better driver spin. There are indeed various additives that make modern golf ball cores more elastic, and those formulae are the secrets the companies take such pains to protect. But those add-ins are also necessary to make the balls come to the proper weight for their size, which is generally 1.68 inches in diameter. Pure polybutadiene would be too light at that size.

So the real competition in cores is in finding ' or developing ' the additives that makes a ball zip for its target swing speed.

Our Z-UR model has an additive called PBDS, a proprietary material that essentially enhances the elasticity, Pai says. Thats for pentabromophenyldisulfide.

Uh-huh. Thanks.

Well, theyre the experts. And thats why Mike moved past my multi-syllabic confusion to change the point of view on the whole modern ball inquiry.

The cover of the Z-UR is 19.7 one-thousandths of an inch.and still durable. And that allows a bigger core within the 1.68 inches, Pai says. Rubber is the most resilient material in a golf ball, and it gives the ball speed, plain and simple. The more of it you have, all things being equal, the more speed youre going to get.

And thin covers do more than just make room for more core.

Its not so much the size of the core, Ogg says. Its the reduction in spin off the driver that you get with a thinner cover. The difference between a 60 thou[sandths of an inch-thick] cover and a 30 thou cover isnt nearly so much a matter of improved resilience as it is a cause of less driver spin.

And as everyone from tour players to tyros has discovered, too much driver spin increases drag, which of course fights lift and robs the tee ball of distance. Keeping backspin under control is one of the four tasks of launch-monitor-assisted club and ball fitting. (The other three are maximizing initial ball velocity, optimizing launch angle, and working with a players clubhead speed.)

Before thinner covers came along, Ogg says, tour quality balls were so spinny that dimples had to be deep to keep spin under control. Those same deep dimples created an undesirable amount of drag. With modern thinner covers, dimples naturally cant ' and dont have to be ' as deep.

Oh, and those covers ' the materials are crucial. Urethane is the material of choice for three-piece balls, which usually include an intermediate boundary layer made of an ionomer. That middle layer does more than just provide a hard surface for the driver to smack against ' it also keeps oxygen away from the rubber core, something urethane cant do. If oxygen reaches the core, the core will oxidize and lose its resilience, like your windshield wipers, Ogg says.

Thats why two-piece balls dont use urethane covers. Instead, they use softer ionomers such as DuPonts Surlyn (an ‘ionomer-class thermoplastic resin,’ as DuPont’s Surlyn website calls it), or urethane-elastomer combinations. Either can be made appropriately soft for short-game satisfaction, while still keeping oxygen from the core.

Now, we all know that golfers from the ancient Scots to that guy Scott in your Saturday foursome have never given a tinkers dimple for core size, cover thickness, or any of that stuff. They just want performance. But knowledge is power, and all that information on the back of the ball box means something. Shop wisely, or at least narrow your field of trial-and-error options.

Not all multi-layer performance balls are going to work for all players, says Pai. The high-compression balls are definitely not going to work for an 85-mph swinger. If you cant deform the ball enough because the balls too firm for your swing speed, youre going to lose distance.

And if you know what to buy, youll gain it. Now, put down that hacksaw.

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