BYK W 907 is a wetting and dispersing additive that improves filler wetting and increases filler load, especially for highly filled systems. BYK W 907 allows for reduction in resin content by 5-10% depending on the formulation while maintaining mechanical properties like flexural strength. BYK W 907 has been specially developed for systems filled with a very high amount of quartz based on unsaturated polyester resins. It improves the wetting of the filler and allows the already high filler load to be increased further, thereby reducing the total costs of the formulation.