Coatings Cafe
Mottling
Defect Description
Paint Mottling happens typically when the color coat, typically metallic colors, exhibit uneven application.
Paint, especially metallic colors, when applied unevenly will have areas of high effect pigments bunched together. The effect is very strong typically if the paint is applied very wet and the effect pigment-like aluminum flakes are attracted to each other. The defect can be seen as uneven areas blotches or clouds in the paint. The term mottling means to mark with spots or smears of color. The defect can appear as stripes in long and narrow areas of wet application.
Also known as: stripes, tiger stripes, clouds, clouding, banding, flooding, blooming
Possible Causes of Defect
1. Film build is too high, especially metallic basecoats
2. Paint Viscosity is not to target
3. Target Distance is too close
4. Poor Booth balance for temperature and air flow
5. Check booth temperature and %humidity, especially for waterborne coatings
6. Application not evenly directed to target
Tips to Avoid Defect
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1. Apply proper thickness
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2. Run with target paint viscosity at application temperature
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3. Maintain proper gun distance
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4. Maintain proper application window
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5. Maintain paint booth temperature and humidity
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6. Set-up applicators directed evenly to target
How to Repair the Defect?
- Consult your specific paint shop procedures.
- Finesse Deck: Sand plus 2-step Polish
- Spot Repair: Sand plus Repaint