How Do Laundries Tackle Oil-Based Stains?

Oil-based stains are one of the problems in the daily tasks of the laundries. Also, there are differences between oil-based stains. If people want to remove stains, they need to be capable of identifying stains.

Identification of Stains

The oil-based stains are “pure” grease. They are usually mixed with other ingredients (pigments, seasonings, dust, etc., from dishes). According to the resources, there are three types:

· Animal oil stains

There are two common kinds of stains: One is the natural secretions of the human sebaceous glands. The other is the animal-based food oils.

The main ingredient of this kind of oil-based stain is saturated fatty acids, which have strong adhesion to all kinds of fibers. This makes them difficult to remove in the normal water washing. They are the type of grease stain with the highest proportion on clothes. If people carefully sniff the stains, they will distinguish the smell of food fats (such as meat or milk) or the distinctive smell of human sebum. The color of the stains is mostly light yellow to dark yellow.

· Vegetable oil stains

They mainly come from cooking oils and some daily chemical products containing vegetable oils. These stains are mostly composed of unsaturated fatty acids, which have relatively poor oxidative stability. If the stain stays on the fabric for a long time, the oil will have oxidative rancidity and have a distinct “rancid smell” (an unpleasant odor caused by oil spoilage). Such stains’ colors are usually light, mostly transparent, or pale yellow.

· Mineral oil stains

The mineral oil stains are not commonly seen on daily clothes. They are mostly on the garments in specific industries (auto repair, mechanical processing, gas stations). They mainly include various fuel oils (gasoline, kerosene, diesel) and lubricating oils (engine oil, grease, lubricating grease). 

Their colors are usually dark (brown, black). They may sometimes have the color of the oil itself. They have a strong, unique chemical odor of mineral oils. Stubborn mineral oil stains may be moist before cleaning. If you use your hands to touch the stains, the stains may transfer to your hands. Typically, such stains are insoluble in water and may have high viscosity.

How to Remove Different Oil-based Stains

· Organic solvent

It can be applied to most pure or flesh oil-based stains (whether it is animal oil stains, vegetable oil stains, or mineral oil stains). This is because the oil is insoluble in water, but it can dissolve in specific organic solvents. 

The usually used organic solvents:

Dry-cleaning solvent (perchloroethylene, hydrocarbon solvents)

Gasoline (pay attention to safe ventilation and flammability)

Turpentine (often used to remove resin-based stains and also effective on oil stains)

Specialized oil-stain pre-treatment agents

· Special stain removers

Stains like ballpoint pen marks (oil-based ink), printing ink stains, oil paint stains, lipstick stains (containing pigments and wax), mascara stains, and certain mixtures of food pigments and oils (ketchup stains, curry oil stains) consist partially of oil. More often, oil is a carrier, and many other contaminants adhere to the fabric.

For such stains, people can use specialized stain removers designed to break down specific types of stains (pen stain removers, lipstick stain removers, ink removers). These products typically contain active ingredients that can break down both oil and pigments simultaneously.

· Detergents

Detergents are suitable for relatively “conventional” oil-based stains (tablecloths and napkins in restaurants that easily have severe oil stains). The surfactant molecules in detergents can reduce the surface tension of water, encapsulate (emulsify) the grease, and disperse it in water to be washed away.

Conclusion

Although the oil-based stains are stubborn, people can perfectly solve the stain problems by mastering the characteristics of different oil-based stains, flexibly adopting organic solvents, and doing the stain removal and washing according to the characteristics.