I am a novice coatings formulator currently comparing formulations for exterior acrylic coatings, and I’ve encountered a practical dilemma: how exactly should I choose between pure acrylic emulsions and styrene-acrylic emulsions?

Technical data shows differences between the two regarding weather resistance, hardness, flexibility, water resistance, and cost. However, when actually developing a formulation, it feels like one cannot rely on a single parameter alone.

For instance, when dealing with cement mortar or concrete exterior walls, factors such as substrate adhesion, coating film flexibility, and water resistance are just as important as weather resistance.

I have recently reviewed product data from suppliers—such as the acrylic and styrene-acrylic emulsions from Celotech and Ruico—and compared parameters like Tg, MFFT, and solids content.

I would like to ask those with practical formulation experience: which parameters do you prioritize when selecting an emulsion? In what scenarios are pure acrylic and styrene-acrylic emulsions typically used?