Defect – Brush marks

Causes

• Improper flow of the applied coating.


• Applying paint at high viscosity.


• Continued application over a long period.


• Application with a dirty, clogged brush.

Prevention

• Apply paint at the correct recommended viscosity using correct thinner.


• Apply paint quickly and evenly.


• Use clean good quality brushes.

Cure

• After the coat has dried, rub down the surface to smooth and uniform level and carefully recoat.


• A Defect – Chalking.

Defect – Chalking

Causes

• Under bound coatings chalk on exposure to weathering.


• Paints applied over insufficiently sealed, porous surfaces.


• Paints not correctly pigmented for specific end use.

Prevention

• Ensure complete sealing of porous surfaces.


• Avoid using inferior quality paints.


• Do not mix undercoats into finishes.

Cure

• The fine powdery film can be removed by wiping and apply a fresh good quality top coat.

Defect – Sagging

Causes

• Applying coatings at incorrect viscosities, film thickness.


• Using improper thinner for thinning.

Prevention

• Care should be taken to apply coats at recommended film thickness and application viscosities.

Cure

• Rub down the sagging parts and recoat carefully.

Defect – Drying not proper

Causes

• Application in unsuitable weather (frosty, cold, humid etc.).


• Improper ventilation Applied over oily, greasy, or unhardened surfaces.


• Using long stored paints in which there are chances that the driers are absorbed by pigments making them non functional.

Prevention

• Always apply in a dry, warm climate with sufficient air circulation.


• Ensure proper cleaning of the surface free from oil grease.


• Add slight excess of cobalt and lead drier.

Defect – Efflorescence

Causes

• Soluble salts from the substrate brought to the surface by solutions of fresh coats.

Prevention

• Do not apply coats on damp moist or freshly plastered surfaces, highly alkaline plasters.

Cure

• AWipe off the deposited salts completely from the surface and ensure no more deposition before recoating.

Defect — Flaking

Causes

• Surfaces having non uniform expansion and contraction causing undue stress.


• Application over powdery or chalking undercoats.


• Application over dirty greasy surfaces.

Prevention

• Ensure that all surfaces are thoroughly clean and dry surfaces.


• Use the recommended primers and undercoats.

Cure

• ARemove all loose paint by scraping and sanding.

Defect — Peeling

Causes

• Subsequent coats before the previous coat has cured.


• Application of paints containing strong solvents which softens the previous coat.

Prevention

• Ensure that the previous coats are thoroughly dried.


• The primer, undercoat and top coat should be entirely compatible.

Cure

• Scrap the entire disintegrated system and rework freshly.

Defect – Loss of gloss

Causes

• Application on greasy, oily surfaces.


• Using inferior quality non compatible thinners.


• Applying over badly prepared porous surfaces and inferior uncured undercoats.

Prevention

• Ensure that the surface is well prepared, free from dirt, oil, grease etc.


• Apply over good quality primer undercoat and under warm dry atmosphere.

Cure

• Add small proportion of cobalt drier or antiskin agents.


• After flattening the surface, apply a fresh coat of top coat of clear varnish.

Defect – Low coverage

Causes

• Thinning beyond recommended volume.


• Recommendation wrt number of coats not followed.


• Surface preparation i.e. primer/putty not as advised.

Prevention

• Adopt painting guidelines as specified in the product literature/container.

Cure

• Add small proportion of cobalt drier or antiskin agents.


• After flattening the surface, apply a fresh coat of top coat of clear varnish.