Sustainable Testing of Paint and Coatings

Importance of the topic

Paints and coatings represent a critical industrial sector with growing market demands. They provide protective, decorative, and functional solutions across automotive, construction, and consumer products. Ensuring quality and sustainability in formulations is vital to meet regulatory requirements and complex application specifications. Vis–NIR spectroscopy offers a rapid, nondestructive, and eco-friendly analytical approach to streamline quality control workflows in paint manufacturing.

Study objectives and overview

This white paper explores the application of visible–near-infrared (Vis–NIR) spectroscopy for multiple analytical challenges during paint and coating production. It aims to demonstrate how Vis–NIR can replace or augment traditional wet chemical methods by delivering high-throughput, multi-parameter analysis from raw material inspection to final product validation.

Used methodology and instrumentation

Vis–NIR spectroscopy instruments capture absorbance spectra across the 400–2500 nm range.

• Measurement modes: inline, online, at-line, offline
• Key features: nondestructive sampling, minimal or no sample preparation, simultaneous multi-component detection
• Reference methods for model calibration: titration, chromatography, colorimetry, pycnometer, rotational viscometer

Main results and discussion

The paper presents case studies covering pigment quantification, dye analysis in inks, additive profiling, amine value detection in dipping paints, and cosolvent measurement in water-based coatings:

• Pigment and dye quantification achieved R²>0.99 correlation between Vis–NIR predictions and reference titrations for dye concentrations in ballpoint pen inks.
• Paint drier analysis delivered accurate values for specific gravity, solid content, metal concentration, and dynamic viscosity in line with ASTM standards.
• Binder quality control: amine number in electrodeposition paints was predicted with R²≈0.97 and low validation error.
• Solvent content: butyl glycol and propylheptyl alcohol in water-based formulations were quantified with standard errors below 1%.

Benefits and practical applications of the method

Vis–NIR spectroscopy enables single-scan determination of both chemical and physical parameters, reducing analysis time to seconds and eliminating hazardous reagents. It supports high-throughput raw material verification, at-line process monitoring, and final product quality assurance, thereby improving safety, lowering operational costs, and minimizing environmental impact.

Future trends and potential applications

Advances in chemometric modeling and miniaturized Vis–NIR sensors will broaden adoption across paint and coating facilities. Integration with process analytical technology (PAT) frameworks and machine learning algorithms will enhance prediction accuracy and enable real-time formulation adjustments. Sustainability-driven regulations will further propel the shift toward nondestructive, reagent-free analytics.

Conclusion

Vis–NIR spectroscopy offers a versatile, economical, and environmentally friendly solution for quality control in the paint and coating industry. By consolidating multiple analyses into rapid, nondestructive measurements, it addresses increasing formulation complexity and stricter regulatory demands while reducing waste and operational costs.

Used instrumentation

• Visible–Near-Infrared spectrometer (400–2500 nm)
• Inline, online, at-line, and offline sampling accessories
• Supporting reference instruments: titrator, chromatograph, colorimeter, pycnometer, rotational viscometer

Reference

• Koleske, J. Paint and Coating Testing Manual (2012), ASTM International.
• Gupta, A. Determination of optimal drier quantities in paint formulations (2013), International Journal of Engineering, Science and Technology.
• Metrohm Application Notes AN-NIR-026, AN-NIR-029, AN-NIR-030, AN-NIR-033.
• Detiveaux, S. & Bangert, C. The State of the Global Coatings Industry (2016), Products Finishing.