Paint Application Techniques and Standards

Paint Application and Problems

• Fish eye eliminator enhances paint smoothness by addressing craters or holes in the paint film.
• Spot repair foam tape is removed after clear coat application and after the last coat has flashed, ensuring a smooth finish.
• Low gloss in paint often indicates surface irregularities such as checking or micro cracking, requiring detailed inspection with a magnifying glass.
• Industrial fallout or acid rain causing discoloration must be fully removed before repainting.

Paint Thickness and Standards

• Paint thickness is measured in mils (thousandths of an inch); OEM paints typically range from 3 to 6 mils.
• Paint build-up should not exceed 12-14 mils to avoid issues in adhesion and appearance.

Metal Treatment and Primers

• Immediate treatment of metal substrates is crucial to prevent corrosion.
• Auto manufacturers employ a multi-stage zinc phosphate treatment for primer adhesion on metal surfaces.
• E coat serves as a paintable primer crucial for factory corrosion protection; it should remain unless manufacturer directs removal.
• Self-etch primers improve paint adhesion and corrosion resistance by chemically bonding with bare metal.

Spray Gun Functionality

• A spitting spray gun leads to poorly atomized paint, causing large droplets and spattering due to air entering the paint stream or loose parts.
• A leaking spray gun can cause paint seepage, often due to dry paint on lid sealing surfaces; maintaining clean sealing areas is essential.

Etching and Sealers

• Etching primers should be used on bare metal with surface rust or pits; plain primer may not adequately fill rust pits.
• Sealers, available in clear or tinted versions, should only be applied over repaired areas and can help match color with semi-transparent coats.

Adhesion and Flexibility

• Adhesion promoter/mid coat primer enhances adhesion on factory baked finishes, preventing lifting and peeling.
• Paint flex additives allow cured paint to remain flexible, although they can dull gloss when compounding is performed.

Flash Times and Conditions

• Flash times vary based on the type of material, temperature, and humidity; modern urethane and catalyzed products usually recommend flash times of 10-20 minutes.
• Cold environments increase flash times while warm conditions can reduce them, but never exceed 100°F between coats.
• Excessive flash times can lead to adhesion and flow issues; short flash times may cause running or sagging.

Testing and Spray Techniques

• The finger flash test checks if paint is dry enough for additional coats; semi-cured paint will stick to a gloved finger if flashed correctly.
• Various spray gun techniques include mist coat, medium coat, full wet coat, and blend coat, allowing for varied finishes in paint application.

Types of Paint

• Acrylic urethane is preferred for durability in topcoats, offering improved strength over standard acrylic enamels.
• Solid color paints are void of reflective flakes, making them easier to spray and match than metallic or pearl options.

Additional Considerations

• Adhesion promoters do not need to be applied over sealed areas, simplifying the preparation process for new paint layers.