It is important to mention that even though special procedures and rules have been set up to maintain a certain batch to batch consistency, the formulation and reproducibility of metallic effect powders in production is more difficult than for smooth solid colours, leading to possible small variations between batches.
Bonding or dry-blending are common processes used to obtain metallic effect powder coatings. While dry-blending involves blending effect pigments and powder basecoat together (metallic particles are free from the basecoat leading to some possible product instabilities), bonding process involves bonding effect pigments to powder particles at a controlled temperature, helping to improve the stability of the final powder.
Once developed, the final aspect of Axalta metallic powder coatings might also depend on the process and the spraying conditions such as:
- charging equipment
- corona or tribostatic
- from various manufacturers
- level of powderguns settings kV/µA (the lower the more metallic the aspect in general)
- type of nozzles
- powder reclaim
- spraying distance
- object orientation
- stroke directions
Once defined, these settings and parameters should be as stable as possible and regularly controlled. This technical document is intended to help the user to apply these coatings. Because of the possible influence of many parameters on the final result, care must be taken to keep the process and spraying conditions as stable as possible for each job, even more so if further applications will be done for the same job. In this regard, we advise using a single batch of powder to coat the whole job. Despite the great care taken during our manufacturing process, some small batch to batch variations may occur. These variations could lead to visible differences in color and appearance when parts coated with different batches of powder are subsequently fitted together. Furthermore, if the job is extended at a later date, or parts are refurbished, we recommend that the color and appearance of new parts are checked carefully to ensure that they are an acceptable match to the existing ones. If a new follow-up order concerns an extension of work, please indicate the previous batch number used (production number) to Axalta to evaluate the feasibility. A subsequent check on the customer production line is mandatory to confirm suitability.