Unique Glove Design Uses Urethane To Help Skiers Get A Grip On Cold Weather

Easthampton, MA — It is a beautiful crisp cold day, perfect for skiing. From the top of a snowy mountain, the slope stretches away invitingly below. The only problem? Cold hands and stiff fingers, numb from the long ride up on the chair lift. However, a new type of glove designed specifically for skiers can make cold hands a thing of the past.

These premium ski gloves, based on a design originally used by astronauts, feature a thermoplastic polyurethane "liquid heat transfer" bladder filled with an oil-based fluid. This hand-shaped bladder absorbs heat generated by an iron oxide heat pack, and spreads the warmth evenly over the entire hand for several hours at a time.

The polyurethane bladder is fabricated by Sealtech, Inc., Athens, Tenn., a custom contract manufacturer, and made with Stevens Urethane sheet from Stevens Urethane, Easthampton, Mass. Through a special conversion process, Sealtech combines sheets of Stevens Urethane, pressure sensitive adhesives, and an oil based solution to produce the filled bladder. The bladder is later inserted into the ski gloves during the manufacturing process.

The glove design includes a built-in pocket for an iron oxide heat pack, commonly known as a "hand warmer" which can be found in almost every ski shop. When the heat pack is activated and inserted into the glove's pocket, the wearer simply clenches his fist or moves his hand. This moves the fluid in the bladder over the heat pack, which warms it up, and distributes the warmth across the entire hand.

Although it seems a simple design, there were a number of critical factors to consider when choosing the bladder material. Sealtech specified Stevens Urethane as the best choice for the application.

"This is a high quality glove, and it had to be designed to last," said Jim Clare, national sales manager at Sealtech. "Durability and flex fatigue resistance are essential, since the wearer must close his hand frequently to keep the oil moving over the heat source. Polyurethane was the only material durable enough to withstand this flexing during the long life span of the glove. We also found we could use a thinner gauge of urethane when compared to other materials such as PVC, which is important for streamlining the glove design and making it easy to wear."

Sealtech uses a polyester grade of Stevens Urethane, which offers exceptional oil resistance. The eight mil sheets provide the optimum combination of performance and fit. By contrast, a vinyl material would have to be a bulky 20-25 mil thick to achieve the same performance.

In addition to flex fatigue, there were temperature considerations to keep in mind. Although the bladder is shielded by fabric, the ski slope is naturally a very cold environment, and many people are on the slopes for a long time before they turn to a heat source. Wind chill is an added factor, as skiers race down the mountain. Therefore, the gloves must endure very low, even sub-freezing temperatures, and withstand repeated cold and hot cycles, all of which added to the list of reasons for choosing urethane. Because urethane is free of plasticizers, which can cause brittleness and cracking in cold conditions, its performance is unaffected by either cold or temperature changes.

"Feel and flexibility were also critical in designing these gloves," noted Clare. "We needed a material with strength and durability, and with high oil resistance and low liquid migration, so the bladder would hold up over a long working life. Stevens Urethane has given us all the performance we could ask for." Clare also noted that in the four years the gloves have been offered, there have been no issues or returns due to bladder failure.

The gloves are also finding new applications, particularly in the military. This technology has been adapted for use by Air Force and Navy fighter pilots to help keep their hands warm in airplane cockpits, as well as for survival equipment during water landings and bail outs. In addition, a modified version is being considered for flight deck crews, where the gloves and bladder have shorter fingers to free the wearer's fingertips for delicate precision work.

Stevens film and sheet can be manufactured in thicknesses from .001 inches to .125 inches and in widths from 5 inches. Tensile strength up to 10,000 psi assures reliability and durability over a long working life, and urethane film and sheet can elongate significantly and still return to its original dimension with no loss of "memory." Stevens Urethane is available in hardnesses from 75 to 95 Shore A, and in a range of standard and custom colors, opacities and surface textures. It can be formulated to meet specific application demands.

Sealtech, Inc., a custom contract manufacturer, specializes in product design and development of radio-frequency sealed plastic parts for the medical, industrial, military, recreation, and transportation markets. Founded 25 years ago, Sealtech is now a division of P. I. Inc. For more information contact Jim Clare, P.O. Box 1067, Athens, TN 37371. Phone: (423) 744-8000. Fax: (423) 744-1364.

Stevens Urethane offers a full range of high-performance urethanes for use in a wide variety of "can't fail" applications for the consumer, medical, commercial, and industrial markets. Stevens Urethane is the only company in the world that offers urethane in blown film, extruded sheet, tubing, cord, and profile form.

For additional information, contact: Stevens Urethane, 412 Main Street, Easthampton, MA 01027. Phone: (413) 533-8100, or toll free at 1-877-TPU-FILM (1-877-878-3456). FAX: (413) 552-1195. E-mail: info@stvure.com. Stevens Urethane is a business unit of JPS Elastomerics.