PEELING – FROM GALVANIZED METAL:

DESCRIPTION

Paint that has lost its adhesion to a galvanized metal substrate

 POSSIBLE CAUSE

• New galvanized metal, a product used to make corrugated sheets, gutters, and downspouts, is usually smooth and is coats with a layer of oil surface will peel quickly.
• Alkyd/oil paints that are applied to galvanized metal will adhere initially, but will quickly fail. The zinc of the galvanizing will chemically react with the alkyd binder of the paint, creating a “soapy” film (saponification) on the galvanized metal causing the coating to peel.
• When galvanized metal is allowed to weather without being painted and is exposed will oxidize in to a white rust until eventually the zinc metal is depleted. The underlying steel will then rust.
• When this oily galvanized metal is painted during cold or highly humid conditions, the curing of the paint film is retarded, resulting in wrinkling and loss of adhesion.

SOLUTION

• The protective layer of oil must be completely removed. Clean Professional Prep Wash Cleaner. Most hydrocarbon solvents, including mineral spirits, leave a thin layer of residue that leads to adhesion failure a thin of the paint film. When cleaning a galvanized surface, use a water-based cleaner/degreaser, such as ProClean Professional Prep Wash Cleaner.
• A weathered galvanized surface develops a layer of white rust, which must be removed to ensure good adhesion of the coating. Wire brushing or scrubbing with a stiff brush or abrasive pad is recommended to remove this.
• Remove iron rust by wire brushing, sanding, or other abrading method: prime bare steel the same day as cleaned. Severely rusted gutters should be replaced.
• Test the coating surrounding any peeled areas out about 6” to 12” to be sure the adhesion is adequate.

SYSTEM

INTERIOR

• Primer, if needed All Surface Enamel Latex Primer, or Galvite HS, or ProCryl
• Universal Acrylic Primer, or DTM Primer/Finish, or DTM Wash
• Primer Finish Refer to our Interior Paint Rating Chart to determine which product best fits your needs.
• Suggested Finishes Cashmere, SuperPaint, Classic99

EXTERIOR

• Primer, if needed All Surface Enamel Latex Primer, or Galvite HS, or ProCry Universal Acrylic Primer, or DTM Prime/Finish, or DTM Wash Primer
• Finish Refer to our Exterior Paint Rating Chart to determine which product best fits your needs.
• Suggested Finishes Duration, SuperPaint, A-100, WoodScapes.
• Most acrylic coatings will adhere directly to cleaned galvanized metal.