The quality control of GEOTECH's special effect pigments
Special effect pigments are complex raw materials. For most products the industry faces a small batch to batch variation which is related to the nature of the products. Depending on the final application these variations need to be addressed with a certain level of attention. In automotive coatings for example very small variations might already be visual in the final product.
In order to maintain high quality standards for special effect pigments it is crucial to have a strict, reliable and extensive quality control (Q.C.) process. All pigments need to be analyzed on batch level. Quality control of special effect pigments is one of the most important daily activities at GEOTECH. Every different product line has its own quality control process. The quality control of glitter for example is different than the quality control of a mica based pearlescent pigment.
GEOTECH's quality control process is documented in over 10 different procedures and instructions. They are part of the quality management system which is based on the ISO 9001 and GMP standard.
Mr. Arthur van Rooyen, Laboratory & Product Development Manager, is responsible for GEOTECH's quality control. Van Rooyen: “To evaluate the visual effect of a pigment we start with the preparation of a wet draw down. The batch is compared to the official product standard. For all products we supply, an official product standard is maintained here in our laboratory in The Netherlands. This method provides immediate insight in the colour, particle size distribution, transparency, gloss and luster of the pigment.
It is a detailed, critical and reliable way to control the quality of our products. If a batch fails in Q.C. most of the times this is based on the draw down. Sometimes the complexity of a special effect pigment in combination with the final application of the customer can make this type of evaluation insufficient. The Q.C. of colour travel pigments, for example, is extended. This is related to the natural quality fluctuation of the pigment production process. In these cases the expected final application purpose of the product also has an influence on the Q.C. method. For these pigments additional tests in powder form and / or nail lacquer are performed.
Besides the visuals, special effect pigments also have additional properties which require a batch evaluation. For cosmetic applications the purity of the pigment is very important whilst stability properties are crucial for plastic applications and solvent based coatings. To guarantee these properties we have developed various procedures to control the quality of our pigments based on the technical requirements of our customers; eg heavy metal analysis are performed for cosmetic products.
All of the product documents, which contain detailed information about product properties, declarations and test methods, are available 24/7 in our online database."