GB/T 21089.1-2007 "Test Methods for Application Performance of Water-based Additives in Architectural Coatings - Part 1: Dispersants, Defoamers, and Thickeners" specifies test methods for evaluating the application performance of three types of water-based additives in architectural coatings, which are applicable for assessing the impact of additives on coating properties. Dispersants are evaluated based on indicators such as grind fineness and tinting strength, defoamers are tested for defoaming speed and persistence, and thickeners are examined for viscosity stability. Testing requires instruments such as grind gauges, rotational viscometers, and high-speed mixers, providing a basis for additive selection and coating formulation optimization.