Technical

2026-09-29

Urethane-Grade Ethyl Acetate: Water and NCO Loss

The chemistry is fixed: one molecule of water consumes two isocyanate groups, and the solvent is where most of that water arrives.

Run the ratio on your own NCO content. At 0.01% water in the solvent, the isocyanate consumed is a direct percentage of the solids paid for, and the arithmetic is on the urethane-grade page for any formulation.

Prepolymer dilution and two-component topcoats each carry their own solvent water ceiling, and both sit at or below 0.02%. Pot life is the first symptom when the limit is crossed; viscosity drift follows within the batch.

Before every batch, re-check the solvent by Karl Fischer and run the line dry. A wet hose undoes a week of moisture discipline in one charge.