Aluminum sulfate is often used as an additive in papermaking. In suitable systems, it can support paper sizing, retention and filtration, while helping improve whiteness and overall sheet performance. Iron-free aluminum sulfate is especially useful when better whiteness and lower impurity levels are required. Compared with traditional acidic sizing environments, properly selected products can help paper mills manage process stability and white water treatment more effectively. Buyers should select the grade according to pulp system, pH condition, target paper quality and dosing process.