EDP Coated, Galvanized, and Weld-Through Primer Steel: What They Are and Why They Matter
At Classic 2 Current Fabrication, the quality of your rust repair starts with the quality of the steel. Every replacement panel we manufacture—whether it’s for a classic truck, SUV, or daily driver—is built from machine-formed steel with one of three key coatings: EDP (Electro-Deposit Primer), Galvanized, or Weld-Through Primer. These finishes are engineered for long-term durability, easier installation, and superior corrosion resistance across a range of weather conditions and driving environments.
If you’re repairing rocker panels, floor pans, cab corners, or trunk floors, understanding the purpose of each steel finish helps you make informed decisions that save time, improve performance, and increase the lifespan of your project. This guide explains each coating in depth—what it is, how it works, and how to prepare your panels properly for welding, bonding, and final paint.
EDP Coated Steel: Built-In Protection You Can Rely On
EDP, short for Electro-Deposit Primer, is one of the most common finishes used on automotive replacement panels—and for good reason. It is ready to be prepped, fitted and painted without hours of extra priming.
What Is EDP Coating?
EDP coating is a uniform layer of rust-preventive primer applied to bare steel through an electro-deposition process. After fabrication, each steel panel is cleaned and electrically charged before being submerged in a primer bath. The primer is attracted to the charged panel, creating an even, bonded coating across all surfaces—inside and out.
This process results in a durable black coating that protects the panel from corrosion during transit, storage, installation, and the period before priming and painting.
Key Benefits of EDP-Coated Panels
- Corrosion Resistance: Shields bare steel from humidity, fingerprints, and flash rust.
- Uniform Coverage: Reaches into tight seams and inner curves for complete protection.
- Time-Saving: Panels arrive ready to prep and install, minimizing extra steps.
How to Prepare EDP-Coated Panels for Installation
- For Welding: Sand the weld areas down to bare metal to prevent contamination and ensure a solid weld.
- For Adhesive Bonding: Sand to bare steel where adhesives will be applied to both mating surfaces.
- For Painting: Lightly scuff the entire surface with a scuff pad or sandpaper to create mechanical adhesion for primer and paint.
EDP should never serve as your final finish. Always apply a high-quality automotive primer and topcoat for full protection.
Galvanized Steel: Ideal for Harsh Weather and Road Conditions
Galvanized steel is coated with a layer of zinc that acts as a sacrificial barrier against corrosion. At Classic 2 Current Fabrication, we use 19-gauge galvanized steel in many of our American-made panels—especially where rust is most likely to occur, such as rocker panels, cab corners, and lower fender areas.
What Is Galvanized Steel?
Galvanization involves bonding a layer of zinc to the surface of steel. This layer prevents moisture and road salt from reaching the base metal and protects against rust even when the surface is scratched or exposed.
Our galvanized panels are especially well-suited for trucks, SUVs, and vehicles that see year-round use in northern climates, coastal regions, or any environment where moisture is unavoidable.
Key Benefits of Galvanized Panels
- Superior Corrosion Resistance: Outperforms EDP in wet, salty, or corrosive environments.
- Durability: 19-gauge thickness provides added strength in high-impact areas.
- Ideal for Trucks and Work Vehicles: Excellent for off-road, commercial, and daily-use applications.
How to Prep Galvanized Panels
- Scuff Thoroughly: Zinc coatings are slick—scuff well before primer to ensure adhesion.
- Use Zinc-Compatible Primers: Look for primers designed for galvanized surfaces.
- Weld with Ventilation: Welding galvanized steel produces zinc oxide fumes—work in a ventilated area and wear appropriate protection.
While more resistant to rust than EDP panels, galvanized steel still requires proper prep and top coating to deliver long-term results. All of our galvanized steel parts are made in America. Made In Detroit is more than a slogan for us, it's who we are.
Weld-Through Primer Steel: Protection Between Welded Seams
When two metal panels are overlapped and welded together, the area between them can become a trap for moisture—leading to future corrosion. Weld-through primer solves this problem by providing a zinc-based coating that can be welded through directly while still offering corrosion protection.
At Classic 2 Current Fabrication, many of our structural and inner support panels come in weld-through primer for this exact reason. It’s ideal for restoration work where factory-style plug welds are being used, especially around rocker panels, door frames, and quarter panel seams.
What Is Weld-Through Primer?
This is a zinc-rich coating sprayed onto panels during production. Unlike EDP or galvanizing, this coating is designed to remain in place during welding and allow current to pass through it, enabling strong welds while maintaining a barrier against rust.
Key Benefits of Weld-Through Panels
- Time-Saving: No need to remove coatings before welding lap joints.
- Corrosion Protection Between Panels: Zinc layer protects areas you can’t reach with primer or paint.
- Cleaner Factory-Style Welds: Perfect for spot, plug, and seam welds in restoration work.
Best Practices for Use
- Clamp Panels Firmly: Ensure full contact to avoid weld gaps or weak seams.
- Weld in Stages: Use stitch welding and allow the panel to cool to prevent warping.
- Finish with Seam Sealer: Even with zinc protection, apply seam sealer to prevent moisture intrusion.
Weld-through primer steel is one of the best ways to maintain long-term structural integrity in hard-to-reach areas that are prone to internal rust.
Why Your Steel Finish Matters
Not all steel panels are created equal. Many inferior replacement parts ship bare, with minimal or no protection against corrosion. These parts require extensive prep—adding hours of sanding, priming, and painting before you can even begin installation.
At Classic 2 Current Fabrication, we eliminate that guesswork. Our machine-formed replacement parts are made with high-quality steel and finished with the coating that matches your job—whether that’s EDP for general repairs, galvanized for weather-exposed parts, or weld-through primer for structural joints.
When you choose panels from Classic 2 Current Fabrication, you’re not just buying a part—you’re investing in a longer-lasting, more professional repair.
Browse Panels by Category
We stock thousands of application-specific panels for cars, trucks, and SUVs from the 1930s through the 2000s. Popular categories include:
Each product is backed by expert support and ships directly to our customers.
Need Help Choosing the Right Steel for Your Build?
Call us at 313.534.2886 or chat with our team online during business hours. We’ll walk you through the best options based on your repair method, climate, and vehicle application.
Get rust repair panels that work as hard as you do. Shop EDP Coated, Galvanized, and Weld-Through Steel at Classic 2 Current Fabrication today.