Cement paint composition in building finishes: Which statement best describes typical cement paints used on exterior/interior masonry and plastered surfaces?

Introduction / Context:
Cement paints are widely used for durable, breathable coatings on masonry. Knowing their typical composition helps prevent on-site errors, such as adding deleterious salts or substituting the wrong binder.

Given Data / Assumptions:

• Cement paints are distinct from lime wash and oil-bound distempers.
• We identify the key binder and typical components.

Concept / Approach:
Cement paints use white cement (sometimes blended with mineral fillers and pigments) as the base binder. They are supplied as dry powder to be mixed with water. While pigments are included, their percentage varies with shade and brand; it is not universally fixed at 5%–10%. Hydrated lime is not the base binder in cement paint (that would be lime wash). Sodium chloride is not an ingredient; chlorides promote efflorescence and corrosion risks.

Step-by-Step Solution:

Verification / Alternative check:
Manufacturer technical data sheets list white cement plus mineral fillers and pigments as the core composition; no chloride addition is recommended.

Why Other Options Are Wrong:

• Hydrated lime base: describes lime wash, not cement paint.
• Fixed 5%–10% pigment: oversimplified and not universal.
• 5% sodium chloride: incorrect and potentially harmful (efflorescence).

Common Pitfalls:

• Confusing cement paint with acrylic exterior paints or lime wash.
• Adding salt or unsuitable admixtures attempting to “improve” adhesion.

Final Answer:
They are prepared primarily with white cement as the base binder