3M solutions for protecting metal substrates from corrosion
Corrosion protection is extremely important to the appearance and the long-term integrity of the vehicle structure and value. It is critical to prevent rust and corrosion by using the most up-to-date products and procedures, on the vehicle surface and beneath it. This is the driving force behind our collection of corrosion protection resources from 3M. These standard operating procedures (SOPs) and technical tips have been developed to help you protect your work against corrosion, keep your shop operating at its peak and maintain your speed, efficiency and expertise in collision repair.
These standard operating procedures cover some common areas where preventing vehicle corrosion is crucial. You’ll find information on corrosion protection in non-visible areas, such as the application of cavity wax and achieving a reliable automotive undercoating application. Also included: SOPs for applying anti-chip coating in the collision repair paint shop.
Consistently effective corrosion protection depends on knowledge – not just knowledge about the best procedures for collision repair, but also about how metal stands up in different conditions and environments. Our technical experts provide the knowledge you need.
Cavity wax is critical for restoring proper corrosion protection on internal auto body components, such as rocker panels, pillars and any closed cavities. These SOPs provide simple information on the proper application of cavity wax including recommended 3M products.
This information covers the procedures and best practices for vehicle undercoats, including cleaning and surface preparation as well as undercoat application. These SOPs include recommended products including paintable and water-based undercoats.
Here are the steps for the application of anti-chip coating, ideal for areas such as rocker panels. These SOPs detail the complete procedure for OEM coating removal, filling and sanding as well as coating a test panel and anti-chip coating application.
3M has developed sealers, coatings and adhesives for excellent long-term corrosion protection, and to help specifically match OEM appearances. With the right technical knowledge, they can really bring out the best in your collision repair shop. Here are a few helpful tips.
Customer Challenge: Some of our techs prefer copper weld-through primers for repairs where corrosion protection is important, such as steel welding. Is this product a better solution than zinc-based material?
Technical Tip: Zinc naturally offers sacrificial qualities – it protects iron-containing steel panels via bi-metallic corrosion, essentially corroding in preference to the steel. Conversely, copper actually accelerates the corrosion of steel. For this reason, zinc-based coatings are specified by many OEMs when replacing welds on panels. At this time, OEM automotive manufacturers do not call out the use of copper weld-through primer.
Customer Challenge: We have heard that it’s possible to weld through seam sealer. Can you explain how that works and how it can help our shop prevent corrosion in our repairs?
Technical Tip: Weld sealing procedures are often great solutions for preventing rust and other corrosion in areas that are most exposed to water and road de-icers, like quarter panel wheel openings and lower pinchweld flanges, that also include seams. 3M recommends a single-component direct-to-metal (DTM) polyurethane seam sealer with a long open time. This allows squeeze type resistance spot welding that essentially encapsulates the weld in a water-tight, corrosion-resistant material.
For more information, refer to 3M Weld Sealing SOP (PDF, 163.22 KB)
Customer Challenge: We typically do not seal seams that don’t have seam sealer on them from the factory. Is there a reason I should change that policy?
Technical Tip: It is important to stay current on automotive manufacturer specifications. Many are actually requiring sealing of hem flange and overlap joint seams on replacement panels. Often, these OEMs maintain up-to-date corrosion protection procedures on their website pages and, in some cases, through specific technical bulletins.
For quick reference, visit OEM Recommended Procedures page
Customer Challenge: Our shop uses an internal corrosion protection product, but I’m not sure how much is required or how much to bill for. Do you have some guidelines?
Technical Tip: The most important factor with any internal coating is that it can be efficiently applied to areas requiring protection. Sprayable cavity waxes are an excellent solution, especially ones with spray nozzles and accessories that fit into very tight access areas and deliver a 360 degree pattern of material. 3M recommends three coats of cavity wax to build a coating thickness that meets test standards set by ASTM B117.
For more information, watch our cavity wax application video