Questions and Answers
What is the maximum recommended thickness for paint build up?
What does a low paint gloss typically indicate?
Which type of primer should be applied to bare metal before any other finishes?
What problem can arise from a spitting spray gun?
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What thickness is typical for original OEM paints?
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Which treatment process is commonly used by auto manufacturers for metal surface preparation?
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What is the main characteristic of self etch primers?
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What should be done with any signs of disfigurement or discoloration of paint due to environmental factors?
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What is the primary purpose of an adhesion promoter/mid coat primer?
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Which of the following conditions can increase the necessary flash times when repainting?
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What is the effect of short flash times between coats?
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Which type of paint is recommended for improved durability in urethane enamel topcoats?
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In what situation should excessive flash time be avoided?
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Which method can help determine if a paint film is air dried or not?
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Why should you never adjust the spray booth temperature higher than 100 degrees F?
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What characteristic distinguishes solid color paints from metallic and pearl paints?
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Study Notes
Paint Application and Issues
- Fish eye eliminator smooths paint by addressing small craters in the film.
- Foam tape is removed after applying clear coat once the flash of the last coat occurs.
- Low paint gloss can indicate surface irregularities like checking or micro cracking, requiring magnification for investigation.
- Discolouration from industrial fallout or acid rain must be thoroughly cleaned off.
Paint Thickness and Composition
- Paint thickness is measured in mils (thousandths of an inch); original OEM paints typically range from 3 to 6 mils.
- Paint buildup should not exceed 12-14 mils to prevent issues.
Metal Treatment and Priming
- Immediate treatment of metal substrates is essential to prevent corrosion.
- Auto manufacturers often apply a multi-stage zinc phosphate treatment for effective primer adhesion.
- E-coat serves as a paintable primer, crucial for factory corrosion warranty on new panels.
- E-coat should be retained unless otherwise specified by the manufacturer.
Primer Types and Applications
- Self-etching primers enhance adhesion and corrosion resistance by chemically preparing bare metal.
- These primers should be applied before surfacer, sealer, or other primers.
- Etching primers available for bare metal are suitable for surfaces with rust or pits.
- Plain primer may not sufficiently fill rust pits.
Spray Gun Operation and Quality
- Spitting spray guns fail to atomize correctly, leading to large liquid droplets; usually caused by air entry or loose parts.
- Leaking spray gun lids or caps can ruin paint jobs; dry paint on seals can exacerbate leakage.
- Regular cleaning of spray gun seals and parts is necessary to maintain performance.
Sealer and Adhesion Products
- Spray sealer should only cover repaired areas; can be clear, colored, or tinted to match vehicle paint.
- Tinted sealers are compatible with semi-transparent color coats.
- Adhesion promoters boost paint adherence on hard-baked OEM finishes to prevent lifting during repainting.
Paint Flex and Curing
- Flex additives enhance pliability, preventing cracks in cured paint when bent.
- Compounding may reduce gloss if flex additive is present.
- Flash times for spray materials vary (10-20 minutes is typical); influenced by temperature and humidity.
Curing and Flashing Guidelines
- Cooler environments increase necessary flash times; warm conditions decrease them.
- Insufficient wait time can cause running or sagging, while excessive flash time can impair adhesion and flow.
- Fully cured paint requires scuff sanding for proper adhesion of subsequent coats.
Temperature Considerations
- Maintain spray booth temperature under 100°F between coats and avoid exceeding 150°F during baking to prevent solvent popping and blistering.
- Conduct a finger flash test by touching the paint to assess dryness; semi-cured paint will leave small strings on the glove.
Spray Gun Techniques
- Types of spray gun coats include mist coat, medium coat, full wet coat, and blend coat.
- Acrylic urethane is preferred for durability over traditional urethane enamel topcoats.
- Solid color paints lack reflective elements; they are simpler to spray compared to metallic and pearl finishes.
Compatibility and Testing
- Adhesion promoters do not need application over sealed areas.
- Water-based primers can resolve chemical incompatibility issues; only dry sand them.
- To determine paint type, solvent tests involve rubbing with lacquer thinner; dissolving paint indicates air-dried types, while non-dissolving paints indicate oven-dried or two-part formulations.
- Checking paint hardness reveals differences in cure rates among paint types.
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Description
Test your knowledge on paint additives like fish eye eliminators and techniques for spot repairs. This quiz covers the importance of gloss levels and the identification of surface irregularities in paint finishes. Understand how to address issues like checking and micro cracking effectively.
