How to Choose a Waterborne Epoxy Resin for Zinc-Rich Primers

Zinc-rich primers are the workhorse of heavy-duty anti-corrosion, and the waterborne transition has made resin selection more critical, not less. The dispersion must stay stable at high zinc loading, wet the zinc powder effectively, and dry fast enough for shop throughput.

Self-emulsifying grades for the highest zinc loading

EP138 and EP138-1 are self-emulsifying liquid epoxies (solid 75%) with excellent zinc-powder wettability and salt-spray resistance — the first choice for 2K zinc-rich systems. Pair them with EH3512 or EH3501 hardeners for fast dry and long potlife balance.

High-equivalent and solvent-free options

• EP151 — large equivalent weight, fast drying, ideal where application windows are tight.
• EP159 — 100% solid, solvent-free self-emulsifying epoxy; highest film build with zero VOC contribution from the resin.
• EP136 / EP137 — economical dispersions (52% solid) with proven anti-sinking behavior in zinc slurries.

Typical systems reach 500–1000 h neutral salt spray. Always verify the zinc/pigment volume concentration and add QD004 anti-flash-rust agent (0.5–2%) when spray-applying onto blast-cleaned steel.