Which of the given procedures should be followed before applying paint onto different components of a building?
i) Chalking
ii) Flaking
iii) Removing blisters
iv) Surface wetting
The Foundation of a Good Paint Job: Surface Preparation
The durability and final appearance of a paint job depend almost entirely on the quality of surface preparation. Paint needs a clean, dry, and stable surface to adhere to properly. Applying new paint over old, failing paint or contaminants will lead to premature failure of the new coat. The terms in the question refer to common paint defects that must be rectified before repainting.
📝 Detailed Analysis of the Options
The question lists paint defects and asks which procedures should be followed. This implies we must address these defects before painting.
i) Chalking
What it is: A fine, powdery residue that forms on the surface of paint as it ages and weathers, especially from sun exposure. The paint's binder breaks down, leaving loose pigment particles.
Procedure: This powder must be thoroughly washed or wiped off. Painting over chalking is like painting on dust; the new paint will stick to the powder, not the surface, and will quickly fail. Therefore, removing chalking is an essential preparation step.
ii) Flaking
What it is: The lifting of paint from the underlying surface in the form of flakes or chips. It's a sign of poor adhesion, often caused by moisture or painting on a dirty surface.
Procedure: All loose, flaking paint must be scraped or wire-brushed off until a firm, sound edge is reached. The edges should then be sanded smooth. This is a mandatory preparation step.
iii) Removing blisters
What it is: Bubbles or blisters that form under the paint film. They are typically caused by moisture or heat, which creates pressure that lifts the paint from the surface.
Procedure: Blisters must be cut open, scraped away, and the underlying cause (e.g., a leak) must be fixed. The area is then sanded before priming and painting. This is also a mandatory preparation step.
iv) Surface wetting
What it is: The act of dampening the surface before applying paint.
Procedure: This is generally incorrect. Most paints (latex, oil, enamel) require a completely dry surface for proper adhesion. Wetting the surface can lead to poor bonding, blistering, and other failures. The only major exception is for some cement-based paints or lime washes. As a general rule, this is not a required procedure.
Conclusion and Answer Analysis
Based on standard industry practice, rectifying chalking, flaking, and blisters are all absolutely necessary procedures before repainting. This would make option (a) (i), (ii) and (iii) the most technically correct answer.
The provided answer is (b) (ii) and (iii). While correctly identifying that flaking and blistering must be addressed, it incorrectly omits the equally critical step of removing chalking. This is likely an error in the source material, as failing to remove chalk is a common cause of paint failure.
📊 Paint Defects & Required Preparation
| Defect | Cause | Required Action Before Painting? |
|---|---|---|
| Chalking | UV/weather degradation of paint binder | Yes (Wash/remove thoroughly) |
| Flaking | Loss of adhesion, moisture | Yes (Scrape, sand) |
| Blistering | Trapped moisture, heat | Yes (Scrape, sand, fix source) |
| Surface Wetting | (A procedure, not a defect) | No (Surface must be dry) |