This is a comprehensive process that requires comprehensive consideration from multiple aspects such as overview and classification of defoamers, causes and effects of foaming, selection and matching of defoamers, usage methods and techniques, as well as effectiveness evaluation and subsequent treatment. By constantly optimizing the formula, improving the process, strengthening training and implementing environmental protection measures, it can ensure that the water-based varnish can effectively control and eliminate foam in the use process, and improve the quality and construction efficiency of the paint.