Measures to prevent flash rust in water-based paint films

Thread Content

This post was last edited by Wang Wei2 on 2026-1-31 at 10:07. 1. Accelerated drying: Higher temperatures and lower humidity help prevent flash rust. 2. Coating thickness: The thicker the coating layer, the more likely flash rust will occur; a thick coating slows down the evaporation of moisture, which can lead to contamination of the metal substrate. It is advisable to use substrates that are less prone to flash rust. 3. pH value of the paint: A higher pH value makes it less likely for flash rust to occur; a pH level of around 9.5 is suitable. 4. Effect of different neutralizing agents: Water-based acrylic amino topcoats or water-based epoxy ester anti-rust paints neutralized with DMEA almost never suffer from flash rust. Emulsion-type acrylic coatings neutralized with ammonia are prone to flash rusting even when the pH is adjusted to 9.5; however, by using DMEA to raise the pH to 11, flash rusting does not occur easily even at 90% humidity. The paired electrons on the nitrogen atom in dimethylethanolamine can be captured by metal ions that are capable of losing electrons, thereby preventing further anodization of the metal substrate. The lone pair of electrons on the nitrogen atom in ammonia forms hydrogen bonds with water, resulting in a loss of its ability to donate electrons. 5. Resin systems: Self-drying systems such as styrene-acrylic and pure acrylic emulsions are most prone to flash rusting, whereas water-soluble acrylic and polyester resin systems are less likely to experience this phenomenon. 6. Use of rust inhibitors: Properly selected rust inhibitors can effectively prevent flash rusting. 7. Corrosion-inhibiting pigments such as zinc phosphate and aluminum phosphate not only provide anti-corrosion protection but also help to suppress flash rusting