Plexus® PC-120 Cleaner/Conditioner for Aluminum & Stainless Steel Bonding in Marine Fabrication

In marine and boat-building applications, aluminum extrusions are frequently structural-bonded to stainless steel brackets using methacrylate (MMA) adhesives such as Plexus® MA530 or MA550. Exposure to moisture and salt spray, however, can compromise bond durability if the metal surface is only cleaned with solvent. A North American marine fabricator adopted Plexus® PC-120 Cleaner/Conditioner as a surface pretreatment prior to bonding 6061-T6 aluminum to 304 stainless steel with Plexus® MMA adhesives, aiming to enhance long-term joint durability and salt-spray resistance.

Surface Preparation Process

1. Initial Cleaning

   – Wipe bulk oils and loose contaminants from aluminum and stainless steel surfaces with a clean, lint-free cloth.

2. PC-120 Application

   – Apply a thin, even film of PC-120 by wiping, brushing, or spraying. The formula contains a translucent red dye; a faint pink/red tint on the substrate indicates adequate coverage. Do not over-apply—a heavy dark-red coating may negatively affect bond strength.

3. Flash-Off & Bonding

   – Allow PC-120 to flash off for 1–3 minutes at ambient temperature. Once the surface is dry to the touch and a slight red tint remains, apply the Plexus® adhesive within its specified working time.

Results

• Salt spray testing showed aluminum and stainless steel lap shear specimens pretreated with PC-120 retained high lap shear strength after prolonged salt fog exposure, outperforming solvent-wiped-only controls—making it suitable for marine and exterior structural applications.

• PC-120 dries rapidly at room temperature and can replace routine solvent wipe in many cases, streamlining the surface prep process without slowing production throughput.

• The integrated red dye provides visual confirmation of coverage, helping operators avoid missed spots or over-application—ideal for QC in production environments.

Compatible Plexus® Adhesives

• PC-120 is recommended for use with Plexus® MMA structural adhesives including MA300, MA310, MA320, MA420, MA425, MA530, MA550, MA560-1, MA590, MA830, MA832, and MA920 when bonding aluminum or stainless steel.