Why Does Epoxy Zinc-Rich Primer Powder? How to Deal with It?

Epoxy zinc-rich primer is commonly used in large-scale anti-corrosion projects and is often used in combination with epoxy cloud iron intermediate paint, fluorocarbon topcoat, and acrylic polyurethane topcoat. The cathodic protection function of this paint plays an important role in anti-corrosion projects. However, improper construction or poor substrate treatment can cause the epoxy zinc-rich primer to powder! Below, we will share with you the reasons and solutions for powdering.

Reasons for powdering of epoxy zinc-rich primer

• The water resistance performance of epoxy zinc-rich primer does not meet the standards. It will blister, peel, and powder after being washed by rainwater.

• The substrate has a high moisture content and alkalinity.

• The concrete substrate has low strength and defects such as looseness, sanding, and powdering.

• The dust, oxide film, rust, and other impurities on the substrate are not cleaned properly.

• Low strength or water-resistant materials are used for substrate repairs or leveling.

• The paint is applied too thick, or the second coat is sprayed or brushed before the first coat is dry.

• During the construction process, the temperature is lower than the drying and curing temperature of the epoxy zinc-rich primer.

• The epoxy zinc-rich primer is exposed to rain before it is completely dry, resulting in defects in the paint film.

• Excessive addition of diluent to the epoxy zinc-rich primer.

Prevention measures for powdering of epoxy zinc-rich primer

• Choose products or manufacturers with test reports and certificates of qualification.

• The age of the concrete substrate should be more than 28 days, and the mortar should be more than 7 days. The moisture content and pH value of the substrate should be below 10. Local holes can be repaired with mortar, which should have an age of more than 3 days.

• The concrete substrate must be cleaned thoroughly. If there are looseness, sanding, powdering, etc., use a wire brush to remove them first, and then use water-resistant and high-hardness materials such as cement mortar and putty for leveling.

• The dust, oxide film, rust, and other impurities generated during the treatment of metal substrates need to be cleaned properly. For areas that need repair, use water-resistant and high-hardness materials such as atomic ash for repairs. After the repairs are completed, apply the epoxy zinc-rich primer.

• When the substrate has a high moisture content, wait for it to dry or use drying methods to meet the construction conditions before proceeding with the application.

• When applying the epoxy zinc-rich primer, wait for the first coat to dry completely before applying the second coat.

• The ambient temperature during painting should be equal to or higher than the standard drying and curing temperature.

• Try to avoid painting on rainy days or in areas where rain is expected, or carry out the construction in a well-ventilated indoor area.

• The epoxy zinc-rich primer should be diluted or mixed with water according to the construction standards.

Methods for handling powdering of epoxy zinc-rich primer

Clean the coatings with defects (powdering, peeling, blistering, etc.) thoroughly. Check if there are any problems with the substrate, and after completing the substrate treatment, reapply the epoxy zinc-rich primer.