applying seam sealer to a metal joint
Seam Sealers and Coatings

Solutions, sealed and delivered by 3M

The Science and the Art of 3M Sealers and Coatings

3M seam sealers and coatings are scientifically developed to be simultaneously tough and flexible for long-lasting performance. They range from brushable to sprayable, so you can more easily match OEM appearance in collision repair. You’ll find a sealer for virtually any application – urethane and epoxy sealers and convenient strip and ribbon sealers are just a few. Our selection of coatings includes undercoats, anti-chip coatings and corrosion protection. 3M also offers related products such as applicator guns and metered static mixing cartridges.

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    Standard Operating Procedures (SOPs) for 3M Seam Sealers and Coatings

    We provide SOPs for a complete range of seam sealer and coating applications, all in one place. From general direct-to-metal (DTM) and non-direct-to-metal procedures to achieving specific textures, these photo and video SOPs can help you make your sealing and coating job better, easier and more efficient.

  • icon of worker in hardhat
    Technical Tips for 3M Seam Sealers and Coatings

    Our technical team can help you improve the finished results of your sealing and coating jobs from adhesion to appearance. We can help you with the science of achieving the most effective seal as well as the art of matching OEM textures for invisible repairs.

  • Important Note
    There are of course many factors and variables that can affect an individual repair, so the technician and repair facility need to evaluate each specific application and repair process, including relevant vehicle, part and OEM guidelines, and determine what is appropriate for that repair.

More 3M Standard Operating Procedures for Seam Sealers and Coatings

  • technician making sound deadening patch
    Pre-Made LASD Replacement Off-Body

    View SOPs for recreating and installing Liquid Applied Sound Deadening (LASD) patches and Noise/Vibration/Harshness (NVH) material on parts which have been disassembled from the vehicle body.

    English Download: Pre-Made LASD Replacement Off-Body (PDF, 175 KB)

  • masking prior to applying sealer
    General Seam Sealer Application Non-Direct-to-Metal

    Review SOPs for proper surface preparation and sealer application for non-direct-to-metal collision repair jobs. This process applies for urethane or two-part epoxy seam sealers.

    English Download: General Seam Sealer Application Non-Direct to Metal (PDF, 145 KB)

  • file belt prepping surface for weld bonding
    Weld Bonding (Excluding Door Skin)

    A quick guide to weld bonding, including panel prep, surface prep for spot welding, and the application of bonding adhesive where required. Also includes information on NVH and foam replacement.

    English Download: Weld Bonding Excluding Door Skin (PDF, 166 KB)

  • applying seam sealer as part of welding process
    Weld Sealing

    A quick guide to weld sealing, including panel prep, surface prep for spot welding, and the application of seam sealer. It also includes information on NVH and foam replacement.

    English Download: Weld Sealing (PDF, 163 KB)

  • spray cleaner removing old sealers from components to prep for repair
    Sealer Coating Removal

    Effective removal of previous coatings is vital to the successful application of new ones. Standard methods for removing seam sealer coating in these SOPs include the use of a strip disc and a file belt.

    English Download: Sealer Coating Removal (PDF, 147 KB)

  • applying seam sealer to a roof channel seam
    Preparing and Applying Seam Sealer to Roof Ditch

    This video segment covers SOPs for the application of seam sealer to a roof channel seam (roof ditch) using a two-component primer. Process includes surface preparation, masking, seam sealer application and tooling.

Technical Tips for 3M Seam Sealers and Coatings

Our automotive sealing products have been developed for long-term performance, and to work well with a range of tools and equipment to specifically match OEM appearances. In each case, the right technical knowledge can really bring out the best in our products and in your collision repair shop. Here are a few helpful tips.

    • Customer Challenge: Our shop has always prided itself on creating an invisible repair. Yet the challenges associated with the many different shapes and types of seam sealer applications leave us feeling we could do a better job in this area. What can we do to improve?

      Technical Tip: First off, it’s very important to choose a high-quality seam sealer and to properly prepare the joint – not just to achieve a lasting seal, but to ensure that it matches OEM appearance. Seam sealers are developed for function and form, and both are crucial to the repair performance. Therefore, it’s important to choose the right sealer for the job. You can choose heavy sealers for vertical seams, controlled-flow sealers that limit waste, flexible sealers for joints which are subject to vibration, and many more. 3M recommends using pneumatic-type sealer applicators to produce consistent, continuous beads, and a range of applicator tips to most closely match the beads originally on the vehicle. Another key is to use masking tape to control the outline or footprint of the seam sealer, creating a defined edge.

    • Customer Challenge: We have seen conflicting information on applying a seam sealer over an etch primer. Is it okay?

      Technical Tip: The term “self-etching” has been somewhat loosely used and can mean different things in the collision repair industry. However, true self-etching primers contain an acidic component that can cause seam sealers not to adhere properly and to fail over time. Single-component or so called “self-etch” primers alone are also not a good choice for corrosion protection. Most OEMs use non-acidic primers as part of the many steps they take to prevent corrosion during coating and sealing procedures. Applying seam sealer to a high-quality two-component epoxy or urethane primer or OEM E-coat is the best option. If application to bare metal is the only acceptable method, choose a sealer designed, tested and proven for bare metal application. Dress and clean the welds. Sand and clean the bare metal – you should never apply sealers over dirty surfaces. Always follow your paint company’s procedures for primer application. If you use products not approved by your paint company, it will most likely lead to unwanted results.

    • Customer Challenge: Is it better to apply seam sealers directly to metal, or to painted or primed surfaces?

      Technical Tip: In most cases, primer or E-coat is the preferred substrate for sealers. However, 3M has seam sealer technology using epoxy, urethane and modified silate polymer (MSP) chemistry tested and approved for bare metal and primer applications. Applying seam sealer to bare metal can present some unique challenges for painting. For example, you may find corrosion “hot spots” if primer and paint coatings are not applied adequately at the seam sealer edges (where sealer meets bare metal). Consider this closely during the repair plan, also taking into account that internal sealers are not subject to the same harsh environmental conditions as sealers used for exterior body applications.

      An excellent example of bare metal seam sealer use is during a weld sealing operation (see SOP) that prevents water intrusion between panels. This includes spot welding while the sealer is uncured, which encapsulates the squeeze-type resistance spot welds in an air- and water-tight layer.

Need Help Finding the Right Solution?

These 3M resources are meant to help you save time, save money and get the most out of your collision repair operations. If have additional questions about 3M sealers, 3M coatings or anything related to 3M collision repair products and solutions, we’re happy to help. You can send us a message at the right. Or, if your needs are more immediate (or if you just want to talk shop), we’re ready to chat. We look forward to working with you!