Which one of the following is used as a carrier in paint?
The Importance of "Drying Oils"
The "carrier" in paint, also known as the vehicle or binder, must be a special type of oil called a "drying oil." This doesn't mean it dries through evaporation like water. Instead, a drying oil reacts with oxygen in the air (a process called oxidation) to polymerize and form a hard, solid, and durable film. This film is what locks the pigments onto the surface. Oils that do not have this property are unsuitable for making long-lasting paint.
📝 Detailed Analysis of the Options
(a) Almond oil, (c) Mustard oil, & (d) Olive oil
Oil Type: Non-drying or Semi-drying oils.
Properties: These oils are primarily used for culinary purposes. They have very low concentrations of polyunsaturated fatty acids (like linolenic acid), which are necessary for the oxidation and polymerization process. When exposed to air, they remain liquid or become rancid over a very long time, but they do not form a hard, solid, non-sticky film.
Suitability as a Carrier: Using any of these oils in paint would result in a coating that never properly cures. It would remain soft, oily, and sticky indefinitely, attracting dust and dirt and offering no real protection. Therefore, they are completely unsuitable as a paint carrier.
(b) Linseed oil
Oil Type: Drying oil.
Properties: This is the correct answer. Linseed oil (derived from flax seeds) is the most common and traditional drying oil used in paint manufacturing. It is rich in α-linolenic acid, which readily reacts with oxygen. This chemical reaction transforms the liquid oil into a tough, solid, and resilient film.
Suitability as a Carrier: Its ability to form this durable film makes it the perfect vehicle. It effectively "carries" the solid pigments to the surface and then "binds" them there permanently as it cures. Other examples of drying oils used in paints include Tung oil, Poppy oil, and Soybean oil.
📊 Key Components of Paint Explained
| Component | Function | Examples |
|---|---|---|
| Vehicle / Carrier | An oily, film-forming liquid that binds components. | Linseed oil, Tung oil, Poppy oil |
| Base | The main solid that provides opacity and body. | White lead, Zinc oxide, Iron oxide |
| Solvent | A volatile liquid used to thin the paint for application. | Turpentine, Spirit, Naphtha |
| Extender (Adulterant) | An inert filler to increase volume and reduce cost. | Silica, Gypsum, Chalk, Magnesium silicate |