Weld-Through Primer Guidelines: Toyota/Lexus/Scion

Details Posted on 17 February 2017 | Share:

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Weld-through primers are generally a zinc-based product that are applied to the mating surfaces prior to welding. Corroding zinc forms zinc oxide which protects the steel. This is called sacrificial corrosion. For a quality weld to be made it’s required that the weld-through primer be removed from the direct weld zone before welding the joint when GMA welding. Many OEMs have a position on when and how to use weld-through primer or when it shouldn’t be utilized. Let’s see what Toyota/Lexus/Scion recommends and where this information can be found.

This information can be found in the vehicle-specific body repair manual (BRM) in General ➤ Precautions for Welding. Per the Precautions for Welding document, Toyota/Lexus/Scion states:

• "Apply welding primer to the contact surfaces of the welding areas to protect them from rust."
• "Do not apply welding primer outside of the contact surfaces."
• Does not recommend a specific weld-through primer product or part number.

The Toyota publication, Collision Pros - Winter 2015 (Issue 1) edition, has an article regarding weld-through primer usage. The article states "When using weld-through primers, keep in mind that zinc-based primers are a more suitable material to use than copper-based primers. This is because these vehicles are manufactured using a zinc galvanizing process, and zinc primer bonds to the metal of the vehicles better."

Use the vehicle-specific BRM to determine which type of welding is required for the repair you are performing. Failure to follow OEM procedures sacrifices the safety and quality of the repair.

For additional Toyota/Lexus/Scion information, check out the following pages:
Toyota OEM Information
Lexus OEM Information
Scion OEM Information

Additional I-CAR Collision Repair News you may find helpful:

• Step-By-Step: Accessing Toyota, Lexus, And Scion Repair Information
• Weld-Through Primer Guidelines
• Welding And MIG Brazing Hotspot

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