What Does Oil Repellency Mean?
An oil-repellent material is designed to prevent one or more types of oil from adhering to, or absorbing into, the material’s surface. This repellent quality causes oil to bead and/or roll off the material, which can prevent the material from becoming slippery. This also reduces the amount of damage to the material that extended exposure to the oil would otherwise cause.
Oil-repelling materials are referred to as “oleophobic” materials. They most commonly come in the form of chemical coatings; however, there are also some artificially manufactured materials that can be used to make protective equipment that is inherently oil repellant.
Safeopedia Explains Oil Repellency
Oil repellency is necessary in industries where workers are frequently exposed to oily substances, such as the petrochemical industry. Oil has very low surface tension, and as a result, it tends to spread over surfaces very easily, rather than forming into droplets the way water does. This makes it difficult to clean up and contain oil spills.
Because the slick created by exposure to oil is very slippery, the presence of oil on a floor or other walking surface poses a fall hazard. Oil slicks can also negatively impact the ability of workers’ safety gloves to adequately grip equipment, which could lead to accidents if the worker loses their grip while performing a safety-sensitive task. As such, many types of work gloves offer oil-repellant grips.
A variety of quality tests are recognized for measuring oil repellency. Different materials require different tests; for example, ISO 14419 rates the oil repellency of textile materials. One common type of oil repellency test is the “drop test,” which involves dropping a standardized amount of oil onto a fabric and determining whether the oil is absorbed into it.
A highly oil-repellent textile is able to avoid absorbing oils that have very low surface tension, such as heptane oil, whereas materials that are only minimally repellent are only able to repel oil with moderately low surface tensions, such as mineral oil.
In addition to their use in protecting surfaces and PPE, oil repellency can also be used to improve the quality of air filtration units that are exposed to oily particles. Oil repellency can improve a filter’s efficiency by preventing oily particles from building up on the surface of the filter, and causing any oil that does stay on the surface to coalesce into a bead.