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June 2001 Vol. 16, No. 6   RSS Feed for Undercurrent Issues
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When Gold Doesn’t Glitter and Reynolds Wrap Won’t Do

What’s with metal-lined wetsuits?

from the June, 2001 issue of Undercurrent   Subscribe Now

“ Harvey’s Titanium Foil Neoprene is a solid coating of titanium foil applied directly to both sides of the neoprene sheet. This reflects the cold away from your body while reflecting the heat back onto your body!”

--- www.cmscuba.com.

“In wet suits, the quality of the foam, its thickness, the goodness of fit and the quality of the design and fabrication are the main factors that determine thermal protection of a wet suit. Aging of the material through ultraviolet exposure, repeated compressions and contact with contaminants will reduce the thermal resistance of the suits.

“There have been a number of marketing fads suggesting an increase in the thermal protection of neoprene. A recent craze is metal-coated neoprene. Manufacturers claim the metal coating reflects back body heat. However, without supporting evidence, the scientific community cannot see a basis for these claims. Conditions within a wet suit are not conducive to radiative heat transfer. The tight fit and moisture layer between the skin and suit provide no gap for radiation to occur. The temperature difference between the skin surface and inner surface of the suit is small so there is little to drive radiative heat transfer.

“In fact, with the close contact between the skin and the metal coating, it was even hypothesized that heat conduction may increase and that metal-coated neoprene might be colder. Measurements of thermal conductivity were made comparing neoprene material of the same manufacturer and type with the only difference being the metal coating. The experiments were done in water in a hyperbaric chamber to a maximum depth of 100 meters. The results show that there was no difference between the two materials within the error of the measurement instruments. This supported the scepticism regarding metal-coated neoprene for wet suits.”

That’s what David Eaton, head of the Diving R&D Group at the Experimental Diving Unit at Canada’s Defence and Civil Institute of Environmental Medicine (DCIEM), told the Great Lakes Chapter of the Underwater Hyperbaric Medical Society.

The coating in most metal-coated wetsuits is generally titanium applied over skin-in neoprene. To most divers, the skin-in feature seems warmer than plain nylonlined suits, because the neoprene skin seals more tightly to the diver’s hide, trapping the water and eliminating the effect of new cold water flowing over the body. This skin-toskin contact allows the body to retain more heat, because there is no need to warm as much water as frequently. Some titanium suits don’t even have a solid foil inner layer — they simply have titanium particles in the neoprene. That way, they can get titanium into their name .

Indeed, marketing can be clever. Henderson Gold Core™Wetsuits , for instance, do not contain gold, the metal; rather a gold-colored slippery lining which is applied over the skin-in neoprene. In fact, it contains no metal at all, says Henderson’s Joe Polak, vice president of sales and marketing. He declined to discuss the make-up of this lining, calling it a trade secret. Henderson’s claims that Gold Core provides greater warmth than standard neoprene is strictly based on the thermal barrier provided by skin-in construction. In fact, Henderson’s own literature claims the most important benefit of its Gold Core Technology™is that the ultra low friction surface of its gilt-lined wetsuits allows them to slide on effortlessly. Henderson’s says Gold Core™ suits are lighter weight than standard neoprene, provide greater warmth and dry almost instantl y, providing a dry suit on the second dive.

Interestingly, the gold core technology is trademarked, but not patented, apparently less inspired by space age technology than by credit card marketing. Which is why, we suppose, Liquid Fit, a maker of custom-fit suits, has a similar optional lining called “Platinum.” Harvey’s has a “Kobalt” suit, but I haven’t seen any Cobalt credit cards.

So, it looks to us that the rush to metal, real or imagined, is more of a marketing innovation than a technical one. Here’s how the Diver Discount Catalog www.diverdiscount.com markets the metal:

“ Harvey’s 6.5 mm Titanium Toaster is 5-10 percent warmer than a typical competitor’s 7 mm semi-dry ... comes in ‘metallic’ black and charcoal with reflective silver decals down the arms and legs that spell TITANIUM, to let everyone know you are serious about diving in the latest ‘hightech’ equipment currently available.”

Ah, the truth. It’s as much about being cool as being warm. Which is why titanium was selected over Reynolds Wrap. No one wants that printed on their arms.

---- Ben Davison

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