Chemically resistant gloves are available in a variety of materials including natural rubber or latex, butyl, neoprene, nitrile, polyethylene, polyvinyl chloride, and combinations of these materials. Significant differences exist between various manufacturers’ formulations of the same base material that can affect how their gloves will perform. The form of the material may also affect performance. For example, molded neoprene can have significantly different properties from those of coated neoprene.
Permeation is a process by which a chemical can pass through a protective film without going through pinholes, pores, or other visible openings. Individual molecules of the chemical enter the film, and “squirm” through by passing between the molecules of the glove compound or film. In many cases the permeated material may appear unchanged to the human eye.
Chemical permeation can be described in simple terms by comparing it to what happens to the air in a balloon after several hours. Although there are no holes or defects, and the balloon is tightly sealed, the air gradually passes through (permeates) its walls and escapes. This simple example uses gas permeation, but the principle is the same with liquids or chemicals.
Permeation data are presented in two values:
Breakthrough time and Rate. Breakthrough times (min.) are the times observed from the start of the test to first detection of the chemical on the other side of the sample (for test methodology, see the outside back cover of this guide). These times represent how long a glove can be expected to provide effective permeation resistance when totally immersed in the test chemical.
Permeation rates are the highest flow rates recorded for the permeating chemicals through the glove samples during a six-hour or eight-hour test. These qualitative ratings are comparisons of permeation rates to each other.Degradation is a reduction in one or more physical properties of a glove material due to contact with a chemical. Certain glove materials may become hard, stiff, or brittle, or they may grow softer, weaker,
and swell to several times their original size. If a chemical has a significant impact on the physical
properties of a glove material, its permeation resistance is quickly impaired. For this reason, glove/chemical combinations rated “Poor” or “Not Recommended” in degradation testing were not tested for permeation resistance.
Physical integrity of the glove is also important. A glove that provides excellent chemical resistance without adequate resistance to tears, punctures, or abrasions is of little value. Generally, for a given material, the thicker the film of protective material, the better. However, a thicker material can impair dexterity. Likewise, gloves that are too small can restrict circulation, causing hand fatigue, while gloves that are too large can be uncomfortable and hard to use.
Generally, the types of chemicals used will be the primary factor in selecting the appropriate glove material; however, all factors should be considered in making the final selection.
Because of the differences that exist between manufacturers’ products and the testing methods that are used to rate a material’s resistance to a chemical, most manufacturers or vendors include disclaimers with their lists stating that the data is intended for guidance only. Be aware that even a glove with an “excellent” rating is not impervious indefinitely. By following these guidelines and the manufacturer’s recommendations, skin contact with chemicals can be kept to a minimum.
- Conduct your own test. Turn a glove inside out, fill it with the test solution, and suspend it over a basin. (If the test solution is volatile, conduct the test in a fume hood.) Check periodically for cracking, softening, dripping, or deterioration. The time it takes for signs of degradation to occur is an indication of the ability of the glove to protect your skin.
- Thin vinyl or latex gloves available from the Storehouse are effective only against water-based or other relatively polar solutions–not organic solvents. Neoprene gloves, also available from the Storehouse, provide better protection against many organic substances.
- If you are working with a mixture of chemicals, check the glove material for resistance to each component of the mixture.
- Before you put on protective gloves (even new ones), check them for holes, tears, and other defects, such as softening or deformation, which indicate that physical or chemical degradation has occurred. Latex gloves are extremely sensitive to storage conditions (e.g. high temperatures and ozone). A damaged glove is worse than no glove at all–it can leak chemicals and trap them next to your skin.
- The glove recommended as the best choice may be bulky, stiff, or have other properties that limit its use for detail work. If sensitivity of touch is required, it may be better to use remote handling techniques plus a lightweight pair of disposable gloves, changed frequently.
- Make sure that all open wounds, abrasions, or other breaks in the skin are covered before putting on protective gloves. Some chemicals that do not affect the skin may have severe toxicological effects internally.
- Before reusing gloves, test them again for resistance. Chemicals may have permeated the glove material even though the gloves have been thoroughly rinsed or cleaned.
- Review the Safety Data Sheet (SDS) for the chemicals or products of interest.