HOW TO: Replicate a Caterpillar Seam Sealer Bead

Ryan Marrinan, 3M Application Engineer, shows how to replicate the caterpillar bead often seen around the crush caps on the rear body panels of Toyota/Lexus and Hyundai vehicles. This high arch ripple bead is also seen on front frame rails and strut towers. Ryan provides tips to achieve that look.
Step 1: Prep your seam sealer (00:29)
We’re going to be using our 3MTM Heavy-Bodied Seam Sealer 08308. As always with all of our two-part cartridges, equalize it upward into a paper towel to make sure you’ve got equal parts A and B coming out. Put the static mixing nozzle back on and dispense 2 to 3 inches of material to make sure you’re getting a good mix out of the tip before you apply it to the vehicle.
Step 2: Lay the material (00:52)
For an on-vehicle application, our best recommendation is to caulk out a bead - remember you’ve got two dissimilar panels to create a ripple texture on - and brush the material into that seam to ensure you have a good seal.
Step 3: Replicate the bead (01:14)
Now we’re going to come in on top of it with our bead. One of the keys is to not go too fast. Let the material do the work, you don’t need to move back and forth. Just keep it vertically against the surface and right above the actual material and don’t go too fast. Let the material do the work for you. The material will create that shape, that texture and that look without much effort.
Step 4: You can also apply upright (02:10)
You can also apply this vertically directly on the vehicle and the material will hold its shape. You can draw whatever you want to match the OEM appearance, and it won’t sag, drip, run or fall off the panel. Again, brush out a stroke first, make sure you’ve got a good seal, then apply the material directly to the surface and get a good tight seal. This is important to have good adhesion and good corrosion resistance built right into the product.
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.
Products used in this video:
3M™ Heavy-Bodied Seam Sealer, Part Number 08308
www.3m.com/3M/...
3M™ Static Mixing Nozzle
www.3m.com/3M/...
3M™ Disposable Paper Mixing Board
www.3m.com/3M/...
For more advanced tutorials, check out 3M Collision Repair Academy
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You’ll find courses that will expand your knowledge, deliver practical procedures that you can use right away, and, in many cases, earn you I-CAR credits.
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