Preface
Automotive refinish paint color matching is one of the core technologies in the auto repair industry, especially the mixing of metallic paint and pearl paint, which often determines the success of the repair effect. Many technicians feel confused when facing metal flakes and pearl powder. This article will systematically explain the characteristics and mixing techniques of these two types of special-effect pigments.
Characteristics and Selection of Metal Flakes
Types of Aluminum Powder
The aluminum powder in metallic paint is mainly divided into two categories: leafing aluminum powder and non-leafing aluminum powder:
| Aluminum Powder Type | Characteristics | Application Scenario |
|---|---|---|
| Leafing aluminum powder | Floats on the surface of the paint film, strong hiding power | Solid-color metallic paint |
| Non-leafing aluminum powder | Evenly dispersed in the paint film, shimmers with angle change | Silver paint, chameleon |
Selection of Aluminum Powder Particle Size
- Fine silver powder (10-15μm): Good hiding power, delicate metallic feel, suitable for light color systems
- Medium silver powder (20-30μm): General-purpose, moderate metallic shimmer
- Coarse silver powder (40-50μm): Strong metallic feel, suitable for dark color systems and special effects
Color Matching Principle of Pearl Powder
Interference Effect of Pearl Pigments
Pearl powder (mica titanium) produces angle-dependent color shift effect through variation in titanium dioxide coating thickness. When the coating thickness is:
- 140-180nm: Produces blue interference color
- 190-230nm: Produces red interference color
- 240-280nm: Produces gold interference color
Control of Pearl Powder Addition Amount
The addition amount of pearl powder directly affects the color effect:
- 3-5%: Slight pearl effect, used for transition
- 8-12%: Medium pearl effect, standard color matching
- Above 15%: Strong pearl effect, mostly used for special-effect colors
Note: Pearl powder must be fully stirred and dispersed to avoid sedimentation and caking
1K and 2K Tinting Base Systems
1K Tinting Base (Air-dry Type)
- Characteristics: Single component, air-dried or low-temperature baked to dry
- Uses: Solid color paint, silver paint, pearl paint
- Thinning ratio: 1:1 to 1:1.5
2K Tinting Base (Two-component)
- Characteristics: Must be used with hardener, chemically cross-linked curing
- Uses: Clear coat, hardener-added metallic paint
- Mixing ratio: Tinting base : hardener : thinner = 4:1:1
Practical Color Matching Steps
Step 1: Determine the Base Color
- Query the original vehicle paint code
- Read the formula or fine-tune the formula
- Determine the main color phase (silver powder / pearl powder ratio)
Step 2: Fine-tuning Stage
- Silver type: First add silver powder to adjust depth, then add transparent tinting base to adjust color phase
- Pearl type: First add pearl powder to adjust interference color, then add transparent tinting base to adjust saturation
Step 3: Test Spray Verification
- Spray using a fisheye test panel
- Compare color and metallic shimmer after drying
- Adjust until consistent with the original vehicle
Common Problems and Solutions
Metal Flakes Blooming
Cause: Unstable spraying pressure, uneven gun stroke
Solution: Use a 1.3-1.5mm nozzle spray gun, maintain constant pressure and gun stroke speed
Pearl Color Darkening
Cause: Uneven dispersion of pearl powder or insufficient addition amount
Solution: Stir and filter thoroughly, increase pearl powder ratio
Obvious Blending Interface in Transition Spraying
Cause: Thinner at the interface evaporates too fast
Solution: Use slow-drying thinner, apply multiple thin coats at the interface
Conclusion
Automotive refinish paint color matching is a craft that values both experience and technology. Mastering the characteristics of metal flakes and pearl powder, and skillfully using the 1K/2K systems, are the keys to completing high-quality repairs. It is recommended that technicians practice with test panels regularly to accumulate experience in color performance under different formulas.
Further Reading:
- Differences and Selection between 1K Tinting Base and 2K Tinting Base
- Test Methods for Weathering Resistance of Automotive Paint
- Kexin Automotive Refinish Paint Product Series
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- Automotive Refinish Paint Color Matching Techniques: Correct Use of Metal Flakes and Pearl Powder