Copper and related alloys such as bronze oxidize freely. It is common to see “green” parts on boats – as well as buildings, homes and decorations. This oxidation can only be prevented by preparing the substrate and then immediately applying a coating such as ALEXSEAL Clear Gloss (T0125) to prevent oxidation on areas such as through-hull fittings. Copper and bronze may be painted with ALEXSEAL Finish Primer 442 and Premium Topcoat 501 if desired, but is not a very common practice. Most owners/ captains choose to only apply a Clear Gloss to these surfaces in order to protect them from oxidation, and maintain their original color.

Overview of Steps to Prepare and Paint Copper or Bronze:

  1. Thoroughly clean the surface using ALEXSEAL Surface Degreaser (A9091) using the “Two Rag Cleaning Method”. Be sure all detergent residue is rinsed from the surface. Use Wipe Down Solvent (A9049) for final surface preparation, also using the Two Rag Cleaning Method.
  2. Copper and bronze surfaces should then be sanded with 180 - 220 grit paper to cut through to a clean surface and create an adequate surface profile for the primer to bond to.
  3. Apply ALEXSEAL Clear Gloss per TDS recommendations or refer to Premium Topcoat instructions within “Finishing”.

Use the “Application Record” to document your application process, equipment settings and environmental conditions for future reference.