Papermaking in alkaline conditions makes it increasingly harder to size paper with traditional rosin products.
Alkaline sizing agents are more efficient than rosin in terms of the amounts needed to reach equivalent levels of hydrophobicity.
The key to sizing success is to ensure that the cellulose fibers are as reactive to the sizing as possible, because AKD size is strongly attracted to fillers and fines. You need good drying before the size press to get the ketene dimer into a hydrophobic state. Sizing efficiency can be improved by adding certain cationic polymers as sizing accelerators.