White lead, red lead, oxides of zinc, oxides of iron are the substances used in the formation of paints of:
🔬 Understanding the Constituents of Paint
Paint is a complex mixture of several key ingredients, each with a specific role. The question asks to identify the category that includes metallic oxides like white lead, red lead, and zinc oxide.
Paint: A mechanical dispersion of one or more pigments in a liquid medium (vehicle + thinner). When applied, the thinner evaporates, and the vehicle hardens to form a solid, protective film.
⚖️ Detailed Guide to Paint Components
Let's break down the function of each component to identify the correct answer.
(d) Base
Function: The Base is the principal solid constituent, typically a metallic oxide powder. It provides the body and opacity (hiding power) of the paint. It also contributes significantly to the durability of the paint film and helps prevent shrinkage cracks.
Examples: White Lead, Red Lead, Zinc Oxide, Iron Oxide, Titanium Dioxide. This perfectly matches the substances listed in the question.
(a) Vehicle & (c) Carrier
Function: These terms are often used interchangeably to describe the liquid, film-forming component of paint, also known as the binder. It's the "glue" that holds the solid particles (base, pigments) together and adheres them to the surface. It is a liquid, not a powder.
Examples: Linseed oil, Tung oil, Poppy oil, synthetic polymers (like acrylic).
(b) Drier
Function: A drier is a chemical additive that acts as a catalyst to accelerate the drying/curing process of the vehicle. It is used in very small quantities.
Examples: Litharge (a form of lead oxide), Red Lead (in this context, acting as a drier, not a base), Sulphate of Manganese.
Other Important Constituents:
- Extenders/Fillers: Inexpensive powders (like gypsum, chalk) added to increase the paint's volume and reduce cost. They have low hiding power.
- Thinners/Solvents: Volatile liquids (like turpentine, mineral spirits) that reduce the paint's viscosity to make it easy to apply. They evaporate completely.
- Plasticizers: Chemicals that are added to increase the elasticity of the paint film, preventing it from becoming brittle and cracking over time.
💡 Study Tips for Paint Constituents
- Base = Foundation: The Base is the foundational solid of the paint, providing its core structure and hiding power.
- Metallic Oxides are Bases: If you see a list of metallic oxides (Lead, Zinc, Iron, Titanium), think "Base."
- Vehicle = Vehicle/Binder: The Vehicle binds everything together. It's the liquid that stays.
- Drier vs. Base Confusion: Note that Red Lead can act as both a Base (providing color and body) and a Drier (speeding up curing). However, the general category for the group of metallic oxides listed is "Base."