Fungal Growth

Causes of Fungal Growth in Paint

       

• Moisture Accumulation: The primary cause, as fungi thrive in damp conditions. Leaks, high humidity (especially 60% RH), condensation, and poor ventilation create ideal environments for growth.

       

• Low-Quality Paint: Paints lacking fungicides/algaecides or with insufficient biocidal additives are more susceptible.

       

• Organic Residues: Dirt, dust, and organic matter on surfaces provide nutrients for fungi.

       

• Poor Surface Preparation: Painting over existing mold or failing to clean/prime surfaces traps moisture and promotes regrowth.

       

• Shaded Areas: North-facing walls, eaves, and areas behind foliage receive less sunlight, retaining moisture and encouraging fungal colonization.

       

• Alkaline Sensitivity: Fungi grow optimally at pH 5–7. Paints with lower alkalinity (pH 8) are more vulnerable.

     

Treatment and Prevention

       

1. Removal of Existing Fungus: Use a bleach solution (1 part bleach + 3 parts water) or a commercial fungicidal wash. Scrub and rinse thoroughly.

       

2. Address Moisture Sources: Fix leaks, improve drainage, and ensure proper ventilation. Install vapor barriers where needed.

       

3. Repainting with Fungus-Resistant Coatings: Use high-quality acrylic or epoxy-based paints with added mildewcides. Opt for paints with pH 8 to inhibit growth.

       

4. Preventative Maintenance: Regularly clean surfaces, power wash exteriors annually, and ensure adequate sunlight exposure.

     

Chalking

Causes of Paint Chalking

       

• UV Exposure & Weathering: Sunlight degrades the binder, releasing pigment particles as chalk.

       

• Low-Quality Paint: Paints with weak binders or excess pigment chalk faster.

       

• Improper Application: Thin coats, over-thinning, or skipping primer reduce paint durability.

       

• Moisture & Humidity: Damp conditions accelerate binder degradation.

       

• Use of Interior Paint Outdoors: Not designed to withstand weathering.

     

Treatment & Prevention

       

1. Remove Existing Chalk: Clean with detergent or pressure-wash, then dry completely.

       

2. Prime & Repaint: Apply high-quality primer and use exterior-grade UV-resistant paints.

       

3. Prevent Future Chalking: Choose paints with balanced PVC, ensure proper surface prep, and avoid painting in extreme conditions.

     

Blistering

Causes of Paint Blistering

       

• Moisture entrapment beneath the paint film.

       

• Painting on damp surfaces or in high humidity.

       

• Rapid drying in direct sunlight trapping solvents.

       

• Poor adhesion due to grease, dirt, or old paint.

       

• Low-quality or non-breathable paints.

     

Treatment & Prevention

       

1. Repair Blistered Areas: Scrape, sand, and clean the surface. Allow it to dry completely before repainting.

       

2. Address Moisture Sources: Fix leaks, improve ventilation, and ensure waterproofing.

       

3. Repaint Properly: Use breathable acrylic paints and apply under moderate conditions.

       

4. Prevent Future Blistering: Prepare surfaces properly and follow manufacturer drying times.

     

Alligatoring

Causes of Alligatoring in Paint

       

• Incompatible paint layers (e.g., oil-based over latex).

       

• Poor adhesion to glossy surfaces.

       

• Improper drying times between coats.

       

• Aging of oil-based paints.

       

• Excessive paint thickness causing surface stress.

     

Treatment & Prevention

       

1. Remove Damaged Paint: Scrape, sand, or use chemical strippers. Clean the surface thoroughly.

       

2. Prepare the Surface: Sand glossy areas and apply a high-quality primer.

       

3. Repaint Correctly: Use flexible acrylic paints, apply thin coats, and allow full drying.

       

4. Prevent Recurrence: Fix moisture problems and maintain painted surfaces.

     

Damp

Causes of Damp in Paint

       

1. Structural Moisture Penetration: Rising damp, penetrating damp, and condensation.

       

2. Improper Surface Preparation: Painting over damp or without proper damp-proofing.

       

3. Environmental Factors: Persistent high humidity, poor drainage, and thermal bridging.

     

Treatment & Prevention

       

1. Identify and Eliminate Moisture Source: Repair damp-proof courses, seal cracks, and improve ventilation.

       

2. Surface Preparation: Remove affected paint, apply fungicidal wash, and use moisture-resistant primers.

       

3. Correct Repainting: Use breathable or moisture-resistant paints.

       

4. Preventative Measures: Maintain drainage, install vapor barriers, and monitor humidity.

     

Foaming / Cratering

Causes

       

• Agitation: Over-shaking or high-speed mixing introducing air bubbles.

       

• Application Factors: Vigorous rolling, thick coats, or hot surfaces.

       

• Material Incompatibilities: Contaminants or incompatible thinners.

       

• Environmental Conditions: Low humidity or poor ventilation.

     

Treatment & Prevention

       

1. Immediate Correction: Break wet bubbles with brush tip, sand dry paint smooth.

       

2. Proper Mixing: Allow paint to deaerate and avoid excessive shaking.

       

3. Surface Preparation: Degrease and tack-clean surfaces.

       

4. Application Techniques: Maintain proper film thickness and avoid over-rolling.

       

5. Environmental Control: Paint between 15–29°C with 40–70% RH and proper ventilation.

     

Frosting

Causes

       

• Moisture exposure or condensation during curing.

       

• Improper paint formulation or incompatible materials.

       

• Poor ventilation and painting below dew point.

       

• Temperature fluctuations and salt spray.

     

Treatment & Prevention

       

1. Remediation: Wash, sand lightly, or completely strip affected coating.

       

2. Environmental Control: Paint above dew point, maintain humidity below 85%.

       

3. Material Selection: Use moisture-resistant and compatible formulations.

       

4. Application Best Practices: Follow recoat windows, use thin coats, and ensure dry surfaces.

     

Lapping

Causes

       

• Improper overlap or inconsistent stroke direction.

       

• Working on too large an area at once.

       

• Fast-drying paints and high temperatures.

       

• Absorbent surfaces or uneven porosity.

     

Treatment & Prevention

       

1. For Wet Paint: Maintain wet edge, re-blend immediately, use thinner if needed.

       

2. For Dried Paint: Sand and repaint entire surface uniformly.

       

3. Preventative Measures: Work in small sections, overlap consistently, and control environment.

     

Efflorescence

Causes

       

• Moisture migration through porous masonry surfaces.

       

• Poor surface prep trapping dampness.

       

• High-alkali substrates or uncured concrete.

       

• Structural cracks and inadequate waterproofing.

     

Treatment & Prevention

       

1. Remove Existing Efflorescence: Brush or wash off salts; use mild acid wash if needed.

       

2. Address Moisture Sources: Seal cracks, fix drainage, and install capillary breaks.

       

3. Repaint: Use alkali-resistant primers and breathable, waterproof topcoats.

       

4. Prevent Recurrence: Allow proper curing, test moisture/pH levels, and use hydrophobic coatings in high-risk areas.