MCQs on Paints and Varnishes

Correct Answer: B. (ii) and (iii)

Solution:

Proper surface preparation is crucial for paint adhesion and longevity. Before painting, any defects in the existing paintwork must be rectified. This includes removing any loose or peeling paint. Flaking (paint lifting and peeling) and blisters (bubbles under the paint film) are common failures that must be scraped off and the surface sanded smooth. While removing chalking is also important, the question treats "Flaking" and "Removing blisters" as the key procedures. The surface should be clean and dry, so "Surface wetting" is generally incorrect.

Correct Answer: D. Cement paint

Solution:

Cement paint is a water-based paint that adheres well to porous, rough surfaces like masonry, concrete, and plaster. It has poor adhesion to smooth, non-porous surfaces. Enamel and aluminium paints are designed for better adhesion on smoother surfaces.

Correct Answer: C. spirit varnish

Solution:

French polish is a classic wood finish that consists of shellac resin dissolved in alcohol (a spirit). It is therefore classified as a spirit varnish. It is applied in many thin layers to build up a high-gloss, deep finish that can fill and obscure minor grain imperfections.

Correct Answer: B. Linseed oil

Solution:

In paint, the vehicle is the liquid portion that carries the pigment and binder. Linseed oil is a classic and widely used drying oil that acts as a vehicle in oil-based paints. Zinc white, aluminium powder, and antimony white are pigments, not vehicles.

Correct Answer: A. varnish

Solution:

This is the definition of a varnish. It is a transparent protective finish created by dissolving a resin (like shellac, alkyd, or polyurethane) in a solvent (the vehicle), such as alcohol, turpentine, or mineral spirits. When the solvent evaporates, it leaves a hard, durable film.

Correct Answer: C. 4, 3, 1, 2

Solution:

The correct sequence for painting is essential for a durable and professional finish. The steps are:
1. Surface preparation (4): Cleaning, sanding, and repairing the surface.
2. Prime coat (3): Applying a primer to seal the surface and ensure adhesion.
3. First coat (1): The first layer of the main paint (topcoat).
4. Final coat (2): The second and final layer of the topcoat for full coverage and color depth.

Correct Answer: A. Binder

Solution:

The binder (or resin) is the film-forming component of paint. It holds the pigment particles together and to the surface once the solvent (vehicle) has evaporated. It creates the solid film and is responsible for adhesion, durability, and gloss.

Correct Answer: D. enamel paint

Solution:

This question describes the property of phosphorescence (glowing in the dark), which is characteristic of luminous paints. Luminous paints are often formulated as durable, hard-drying paints, similar to enamels. Therefore, within the given options, enamel paint is the closest category, as specialty luminous paints can be a type of enamel.

Correct Answer: B. Litharge

Solution:

A drier is a substance added to paint or varnish to accelerate the drying time. Litharge (lead(II) oxide) is a metallic salt that acts as a powerful catalyst for the oxidation and polymerization of drying oils, making it an effective drier. Copal and Mastic are resins, and Turpentine is a solvent.

Correct Answer: D. Lead acetate

Solution:

Driers are metallic compounds that speed up the curing process of oil-based coatings. Lead acetate is a lead-based compound that functions as a drier, promoting rapid and uniform drying. Mastic, Shellac, and Amber are natural resins used as film-formers (binders), not driers.

Correct Answer: C. Paints

Solution:

The Munsell color system is a color space that specifies colors based on three attributes: hue, value (lightness), and chroma (color purity). It is a standard and widely used system for accurately identifying and communicating color, making it essential for the classification and matching of paints.

Correct Answer: C. binder

Solution:

The binder is the component that forms the film and holds the pigment particles. It provides adhesion and binds the paint's ingredients together into a cohesive film that can be spread evenly. The term "vehicle" often refers to the combination of the binder and the solvent.

Correct Answer: B. base

Solution:

In traditional paint formulations, white lead serves as the base. The base is the primary solid ingredient that provides body, opacity (hiding power), and durability to the paint film. While it also has color (white), its main role is to form the foundation of the paint coating.

Correct Answer: A. S1 is false and S2 is true

Solution:

S1 is false: Plastic paints (like emulsions) are water-based, so the thinner used is water, not oil.
S2 is true: Varnish is indeed a solution of a resin in a solvent. Spirit varnishes, for example, use alcohol as the solvent, making the statement true.

Correct Answer: A. (Volume of pigment in paint) / (total volume of non-volatile constituents of paint)

Solution:

Pigment Volume Concentration (PVC) is a fundamental formula in paint technology. It represents the volume ratio of the pigment to the total volume of all non-volatile components (pigment + non-volatile binder) in the paint film after it has dried. The correct formula is:
PVC = (Volume of Pigment) / (Volume of Pigment + Volume of Non-Volatile Binder)
Option A correctly represents this relationship.