The reaction forms an amorphous chromate film over the zinc coating.
To successfully execute an ASTM D2092 preparation workflow, operators should adhere to the following systemic sequence: astm d2092 pdf
ASTM D2092, titled "Standard Guide for Preparation of Zinc-Coated (Galvanized) Steel Surfaces for Painting," provides a systematic approach to cleaning and treating these surfaces. By following this guide, engineers and contractors can prevent premature coating failure, which is often more expensive to remediate than the original application. The Classification of Surface Treatments The reaction forms an amorphous chromate film over
The primary challenge with painting galvanized steel is the presence of surface contaminants and the chemical nature of the zinc itself. New galvanized steel is often treated with chromates or oils to prevent "wet storage stain" (white rust). If these are not properly removed according to standardized procedures, the paint will likely peel or flake within months. The zinc surface is cleaned with an alkaline
The zinc surface is cleaned with an alkaline solution and then treated with a zinc phosphate or iron phosphate solution.
Use alkaline cleaners to remove zinc oxides (white rust) and passivation coatings.
Apply the acidic solution directly to a clean zinc surface to micro-etch the metal and passivate it simultaneously.