TechnicianVision · Knowledge base
Back-To-Basics: Weldable Seam Sealer
I-CAR · May 22, 2025 · Subaru, Nissan, INFINITI
Summary
This article explains the purpose and application of weldable seam sealers, which provide corrosion protection between panel flanges during squeeze-type resistance spot welding (STRSW). It highlights that only specific OEMs require this method, it does not replace 2-part weld bonding adhesives, and the sealers must never be applied over acid-based self-etching primers.
What to do on the job
Verify the OEM body repair manual and product technical data sheet (TDS) to confirm weldable seam sealer compatibility with STRSW, and ensure it is never applied over acid-based self-etching primer.
How to use it
Use this document to justify the necessity and material cost of weldable seam sealers on vehicles where the OEM (such as Subaru or Nissan) explicitly mandates a conductive rust-preventive or spot sealer on mating surfaces prior to STRSW. It can also be used to defend the exclusion of self-etching primers on flanges where these sealers are applied, citing product manufacturer guidelines from 3M, Lord Fusor, and SEM.
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