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July 2003 Vol. 18, No. 7   RSS Feed for Undercurrent Issues
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The Skinny on Wet Suit Shrinkage

or is the problem really calories?

from the July, 2003 issue of Undercurrent   Subscribe Now

"Hey, it looks like your wet suit shrunk over the winter." That gag is so old it's become a diving cliche. But, like most cliches, it contains a grain of truth.

An article in the Journal of The South Pacific Underwater Medical Society recently said: "Divers often complain that wetsuits shrink with age. Certainly, as the air cells in the material collapse as a result of neoprene aging, the suit may become stiffer and therefore less easy to don and less comfortable to wear, but mainly the 'shrinkage' is due to the diver's configuration changing with age!"

Plenty of divers put on the pounds, especially with all those vacation calories. However, two experts at RBX Industries (formerly Rubatex), the largest manufacturer of closed cell Neoprene in North America, take the problem of shrinkage more seriously.

As divers know, wet suits are made from closed cell synthetic rubber (known by the DuPont trade name neoprene), which consists of thousands of tiny cells, each containing bubbles of insulating nitrogen. Roger Schmidt, manager of marketing and technical services for RBX, confirmed that over time the gas bubbles can escape through the cell walls. Two conditions escalate that process in opposite ways. On one hand, exposure to heat, such as intense sunshine, can expand the bubbles so some can actually rupture the cell walls. On the other hand, repeated exposure to pressure encountered underwater, compresses the bubbles to the point where they can permeate walls and escape.

Jeff Ryken, national sales manager for RBX's Laminates Group, puts it this way: "Imagine a bundle of balloons. If the inside ones burst, the outside circumference will retract." Besides retracting, the fabric loses elasticity. Schmidt adds that a shrinkage of just 5 percent could make a difference of four inches in a 72-inch long suit -- or two inches in a 36-inch waist. He adds that linings such as nylon and metallic compounds do not affect shrinkage, one way or another.

If like Seinfeld's George Costanza, you have a problem with shrinkage, how can you select the right suit? The problem is, not all neoprene is created equal. Different formulations with variations in cell sizes and cell wall thickness provide varying resistance to heat and pressure. Since RBX began losing market share to Asian firms, their emphasis has switched to lighter, more stretchable wet suits, which are cheaper to manufacture and ship, and more comfortable to wear. But, the cheaper suits are more likely to shrink. "The consumer buys a suit in the store, not in the water," Ryken points out, adding that professional diver grade suits are more durable, and thus less subject to shrinkage.

However, there are no industry standards for professional divinggrade neoprene. Moreover, it's nearly impossible for a consumer to identify the grade of neoprene when examining a wet suit in the store. Ryken suggests that anyone shopping for a suit should ask the dealer a few questions: "Is this suit appropriate for repetitive deep dives? Have you been using it, and, if so, what has your experience been? Have you had any complaints about this model?" A custom suit maker might be able to select different grades of neoprene for different needs.

To prevent shrinkage, Ryken says to dry your suit in a dive locker or in a dryer at low temperatures rather than in direct sunlight. Besides overheating the foam cells, sunlight will fade any fabric, even a black wet suit.

Now, whether your wet suit did shrink or you're putting on pounds, you can do something about it. The seams can be split and pieces added to give you more room.

Your local dive store can probably help you out because some people make a living expanding wet suits. They can take measurements and forward the suit on. Also, several firms that deal directly with individuals, and work on most brands of suits. We talked with two that provide guidelines for measuring the parts that need alteration. Since each job is custom, prices vary depending on the thickness of the original suit and what needs to be done. Letting a suit out is more expensive than taking one in, because additional fabric must be purchased. Figure 23 weeks turnaround time, especially if new material needs to be ordered.

The Skinny on Wet Suit Shrinkage

Stitchlines of Englewood, CO charges a minimum of $65 plus shipping to expand a waistline and they can do other custom alterations. They even installed a zippered panel in the stomach of a wetsuit for a diver who swore he was going to shed the extra pounds soon. Call at 303-781-9044 or by email at

Otter Bay Wetsuits has a storefront location in Monterey, CA, where divers can be fitted for an alteration or a new custom suit. Or, you can request a video with measuring instructions, have your buddy measure you, then send them your suit. Alterations start at $50 and can run to $250 if both a jacket and farmer John need to be expanded. Check her out at or 888-220-1453.

If your suit still doesn't fit . . . well, Mike's in England, as the ad shows, will be happy to help you.

P.S.: As an alternative to drysuits, Otter Bay Wetsuits owner Ruth "Cricket" Justice is now offering 10 ml. hoods and torsos for farmer John suits, and will soon be producing them in 12 mil.neoprene. She keeps the arms at 7ml or less to retain flexibility.

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