Practical Guide to Wetting Agent Addition Sequence and Dosage in Waterborne Coatings

In waterborne systems, the effectiveness of wetting additives depends not only on selection but also on the addition sequence and dosage combination. An incorrect addition sequence can cause additive interference, foaming or cratering.

Addition Sequence

Recommended sequence: add the substrate wetting agent (BWA-925) and low-foam wetting agent (D-502A) first in the grinding stage to allow full adsorption; add the leveling agent (SI-800) after the let-down stage; add the defoamer (Foamic-024) in two portions — half in the grinding stage and half in the let-down stage.

Dosage Range

Substrate wetting agent: 0.1-0.5% of total formulation; low-foam wetting agent: 0.1-0.3%; leveling agent: 0.2-0.8%; defoamer: 0.1-0.5%. Adjust according to the system resin and application method.

Common Problems

Cratering is often caused by insufficient substrate wetting agent dosage or late addition; foaming is often caused by the defoamer not being added in the grinding stage or excess wetting agent. A small-scale test is recommended first.

Related Products

BWA-925 (substrate wetting), D-502A (low-foam wetting), SI-800 (leveling), Foamic-024 (defoaming).