Color measurement of metallic finishes in the laboratory: BYK-mac i with smart-lab

1. Management of color specifications

For efficient quality control, an easy to recognize Pass/Fail indication is a major benefit. Therefore, smart-lab offers a comprehensive standard management to define color & effect tolerances.

1.1    Setup of master standards with tolerances

Color & effect specifications can be defined by setting up product families with Pass/Fail limits. If needed “yellow” warning ranges can be input giving the user enough reaction time before the product is out of specification. Custom specific color equations of major automotive makers are already predefined and ensure color control according to their internal specification. Or use the latest color difference equations for effect coatings dEDIN6175:2019 and dEComb to develop tolerances for new colors.

1.2    Exchange of digital standards for a seamless workflow

Thanks to the outstanding inter-instrument agreement of the BYK-mac i “digital standards” can be distributed on a global basis. Color standards can be exported in xml file format and send by email to the entire supply chain, making sure that everybody is using the same target and tolerances.

Abbildung 1 Definition of digital master with tolerances and limits

2. Project management of test series

smart-lab uses projects to organize measurement data. In R&D studies are performed to evaluate the influence of material properties, raw material concentration levels and changes of process parameters that can affect color & effect data. For paint batch QC the different corrections steps need to be recorded until color, sparkle and graininess specs are met. To determine the master standard from a population of panels, it is possible to calculate the mean value and use it as the digital standard - of high interest to automotive headquarters.

2.1    Online measurement in the lab

Just connect the BYK-mac i with the PC, measure the master panel, apply the respective tolerances and compare the actual samples against the standard. Alternatively, you can recall a standard and samples from a database and quickly add new readings. The data are instantly displayed in a data table with Pass/Fail information and shown in various color graphs.

2.2    Transfer saved data for detailed analysis  

Or do you want to take the BYK-mac i with you to the production line? No problem either! Standards can be sent to the instrument to conduct color & effect data on site according to the predefined specifications. For further evaluation and documentation, the stored readings can be transferred to smart-lab.

Abbildung 2 List with recently used projects

3. Analysis of color and effect data

smart-lab BYK-mac i offers a variety of professional QC reports to make data analysis easy and comprehensible: data table, CIELAB scatter plot for 6 angles, travel graph and trend line.

3.1    CIELAB plot with data table and traffic light function

Color difference data for up to 6 measurement angles are charted in a common CIELAB scatter plot. Tolerances are shown as red and green lines indicating the FAIL and WARNING level. An easy-to-read data table displays the numerical values of the test series. If individual color components are out of specification, the data is colored to indicate the direction of the deviation. Additionally, the Pass/Fail result is symbolized by a green – yellow – red traffic light.

3.2    Sparkle and graininess graph

Like the CIELAB scatter graph, this chart easily shows whether effect differences are within tolerance. One graph per sparkle angle and graininess is displayed. Also here, tolerances are shown as red and green lines indicating the FAIL and WARNING level. Sparkle 15° is influenced by the formulation e.g. flake type and size while Sparkle 75° gives an indication how well the flakes are orientated. Additionally, samples can be organized in different groups e.g. all samples that are visually Pass can be grouped together. For ease of visualization each group is displayed in the same color in the graphs.

3.3    Color Travel to show flop behavior

Color Travel is the ideal graph to show how individual samples perform per measurement angle. Charting the color data for all measurement angles per sample gives an indication of the flop behavior. In combination with a graph for sparkle and graininess values, total color impression can be easily controlled.

Abbildung 3 CIELAB scatter plot for multiple angles

Abbildung 4 Color Travel to show flop behavior

4. Powerful SQL database and data sharing

In a global world, efficient data sharing between different production sites and among the supply chain is essential. Thus, when a project has been completed, the measurement data can be saved in a powerful SQL database which allows handling of large data sets over a long period. The database can either be stored locally or recite on a SQL server with defined access rights for the individual users. All reports can be sent to Excel, printed out or sent by email as a PDF file.

5. Summary

Color and effect control in the laboratory requires a high degree of flexibility in data analysis on the one hand, but also efficient data handling of large data sets on the other. 
BYK-Gardner’s software smart-chart offers unsurpassed functionality to make you ready for professional BIG DATA management: 

• Powerful standard management with digital master standard distribution
• Measurements can be taken online or transferred from the instrument memory
• Professional project management to organize measurement data
• Standard QC reports: data table, CIELAB scatter plot for 6 angles, travel and trend graph
• Powerful SQL database for efficient data handling over a long period

smart-chart has all the tools to make the world of data analysis transparent, easy to interpret and efficient. Make sure to always have the latest version installed on your computer: https://www.byk-instruments.com/en/software.