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Cool hands are safer hands

Supplier: Ansell Industrial Healthcare By: Cherilyn Nelson, PhD.,VP, Fibre & Knitting Technology, Ansell
23 June, 2011

The active and sportswear markets have invested a substantial amount of time and money in fabrics and garment construction that keep us cool and dry.

The active and sportswear markets have invested a substantial amount of time and money in fabrics and garment construction that keep us cool and dry. Industrial glove users and manufacturers also desire these attributes since their work environments—whether indoors or outside—can be hot.

Workers want gloves with features such as breathability, moisture wicking capabilities, stay-dry linings and cooler fabrics that prevent the build-up of perspiration on the hands. This enhances the ease with which they are able to work while continuing to wear their gloves.

While it may seem logical for the occupational glove industry to adopt the technology and techniques used by sportswear manufacturers, there can be challenges to do so as the product composition of industrial gloves is very different.

Fabrics used for active wear are often flat-surfaced, with relatively few fibre types incorporated into a single product. Occupational gloves, on the other hand, are made from many different fibre types and blends incorporated into a large number of yarn structures. These yarns can be knit into single or multi-layer gloves, which, in turn, are dipped into a variety of latexes that can cover all or part of the glove surface.

Measuring the moisture management properties of occupational gloves, therefore, becomes quite a challenge.

Sweaty Hands Extend Beyond Summer

Hot, sweaty hands can be an issue any time of year. Workers handling outside machinery on cold days, for example, may have sweaty hands if the gloves they are wearing do not allow for moisture and heat dissipation.

Sweat is an issue in any job where perspiration becomes "sensible" rather than remaining "insensible." Our bodies lose moisture continuously—even when we are at rest. Because we are generally unaware of this change, the moisture lost is called insensible perspiration. When activity levels increase or the body is in a warm or humid environment, insensible perspiration is replaced by sensible perspiration, or sweat.

Hot, sweaty hands may be an issue in any job that generates sensible perspiration within a glove—whether it is a mining, transport, food service, chemical or manufacturing application. Sweaty hands are also a concern in applications with temperature extremes.

Moisture Hazards

When hands become hot and sweaty, workers' first reaction is to remove the gloves, which may expose the hands to hazards such as sharp edges, abrasive surfaces or chemicals. Workers may also remove their gloves because of unpleasant odours. While sweat from the hands is practically odourless, the glove interior develops odours when the bacteria that naturally occurs on the skin multiplies in the moist environment.

Additionally, sweat build-up on the inside of a glove may adversely affect the skin. The outer layers of the skin can reabsorb sweat, but this causes a reduction in the skin's barrier properties. Reduced barrier properties can lead to more rapid penetration of chemicals that are present in the work environment or in the interior of the glove.

Even when workers remove their hot sweaty gloves, the moisture level in the skin will require time to return to normal levels. During this readjustment phase, the barrier properties of the skin are reduced.

Sweat also impacts dexterity and may cause the gloves to stick to the fingers or bind at flex points such as the knuckle, making it difficult to pick up objects.

Materials, Fabrics May Cause Sweaty Hands

Some materials and fabrics do not promote moisture vapour transmission or liquid water movement (wicking) and will actually contribute to hot, sweaty hands. Absorbent (hydrophilic) fibres such as cotton move liquid moisture away from the skin, which results in an initial cooling sensation. Cotton, however, can hold moisture rather than allowing it to evaporate.

Non-absorbent (hydrophobic) fibres such as synthetics can move liquid moisture by wicking it through the capillaries, which are the small spaces between fibres in a yarn or between yarns in a fabric. For wicking to occur, capillaries must go from one side of the fabric to the other so the moisture can evaporate. Uncoated gloves made from polyester or nylon fibres, for example, have capillaries that go from side to side.

Fabrics with raised surfaces such as napped (brushed) or pile-like surfaces obtained by flocking will result in hot, sweaty hands if the fabric traps and holds moisture vapour or liquid moisture. These fabrics incorporate a substantial amount of air in their structures, which adds to their insulation and makes them feel warm against the skin. Thicker fabrics also promote heat and moisture build-up, as do layered fabrics.

Moisture Management

Moisture management may be achieved by employing certain finishes and various fibres and fibre modifications. Some engineered yarns and fabric structures offer moisture management properties or those yarns and fabrics may be combined with certain technologies —such as using finishes along with altered fibre cross-sectional shapes.

Among the synthetic fibres, polyester, polypropylene and nylon are most often employed in active wear and are widely used in knitted gloves. While all three fibre types are considered non-absorbent (hydrophobic) compared to a fibre such as cotton, they can be modified with finishes to increase their moisture management properties.

Moisture movement depends on the size of the spaces (capillaries) between fibres. Generally, smaller diameter capillaries will have greater surface energy on the inside face, which will cause moisture to move up the capillary to the fabric surface and away from the hands.

Physically modifying a fibre is a less expensive way to introduce moisture management properties to hydrophobic fibres. Changing the fibre’s cross sectional shape and diameter can impact the movement of liquid water through the fabric by wicking and capillary movement.

Choosing Cool, Comfortable Gloves

Many glove manufacturers indicate whether their products will help control moisture. Look for terms such as moisture absorption, moisture wicking or moisture management technology in product literature. Gloves with Dyneema, for example, have been described as lightweight with the ability to keep hands cool and dry.

Some manufacturers offer gloves with an uncoated back, described as allowing air to circulate to keep hands cool. A dialogue should develop between the purchaser and the glove manufacturer to discuss the technology used and its advantages.

Product trial is also important because a single glove style is unlikely to solve moisture management challenges in a variety of applications. Workers should try different gloves to determine which are the most comfortable and effective. Workers must want to wear the gloves and commit to keeping them on the hands if the gloves are going to provide the desired level of protection.