Even though the same paint is used, the color changes between batches. This is a common cause of color variation in metallic coatings for automotive parts.
[Cause of Occurrence] In automotive interior and exterior parts, color unevenness (color variation) such as "the color appears different depending on the lighting" and "there are variations in shade between lots," despite being painted in the specified color, is a major factor that prevents meeting strict appearance standards. [Truth] Particularly with metallic and pearl-type paints, the arrangement of "aluminum pigments contained in the paint" determines the color tone. If the air pressure of the spray gun is unstable or the exhaust airflow in the painting booth is too strong, the pigments do not align uniformly, leading to color unevenness and worsening surface roughness. [Improvement Measures] To maintain a stable color tone, it is essential to stabilize the compressor pressure and optimize the airflow in the booth (approximately 0.3 to 0.5 m/s). A checklist for equipment inspection to prevent color variation and a guide for optimizing spraying conditions can be downloaded below. [Summary] Color unevenness is not due to defects in the paint itself, but occurs when disturbances in the airflow and air pressure of the painting environment disrupt the arrangement of pigments. Eiwa Kogei Co., Ltd. promises high-quality finishes by preventing color variation between lots through the maintenance and management of a stable painting environment.
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basic information
Response: Metallic coating / Automotive interior and exterior parts / Film thickness management: Plus or minus 20 microns / Spraying conditions: Distance 20 cm, Pressure 3.0 kg / Airflow management: Constant temperature and humidity booth / Color variation below 0.1 percent
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Applications/Examples of results
Automotive interior and exterior parts, metallic painted products.
Company information
We are not just a "subcontracted painting factory." Established in 1958, our company has a foundation of painting technology and also specializes in chemical treatment, stripping, and cleaning, functioning as the "external surface treatment department" in your organizational chart. Based on our philosophy of "preparation is eight-tenths of the work," we emphasize participation from the "upstream process" before the drawings are finalized. We conduct test painting on a wide range of metals and difficult materials, and we produce the entire process from assembly, packaging, to delivery, thereby reducing your management workload. Additionally, by being able to perform zinc phosphate treatment in-house, we achieve stable painting quality. Furthermore, our micro-heating stripping technology, which does not use chemicals, maintains the electrical state of the "jigs (hangers)" that influence painting quality. Our approach of "pre-treatment determines painting quality" ensures the stability of the paint film during mass production. Rather than simply "applying specified standards," we work backwards to achieve optimal painting specifications and prevent scratches during transportation, sparing no effort in thorough discussions from the outset. This diligent preparation is the shortest path to preventing rework and minimizing total costs. From the development stage, please utilize the expertise of our specialists as part of your production line.
