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00:00 — Hey, Shawn here from 3M. Thanks for checking out our video today. What I’d like to discuss today is panel bonding.

00:10 — Now I know a lot of you guys have been doing a lot of panel bonding over the years.

00:14 — This is more of a basic intro panel bonding video, but it’s going to cover some topics and some things that we’ve seen in the industry that technicians may be doing incorrectly, or could change a little bit of their process.

00:26 — So I’m going today to use a mock-up panel, this being the host panel, something that simulates something like a frame rail or a panel on the vehicle, and then this would be our replacement panel here.

00:36 — So I’m going to show the steps through the bonding process using these two mock-up parts.

00:44 — I’m going to use 8115 today, but this could pertain to any of our bonding adhesives.

00:50 — So again, I know a lot of you guys have been doing a lot of bonding, but check this out, watch closely, and you might pick up a couple things that you haven’t thought of in the past.

01:11 — So the first thing I’m going to do here is remove the seam sealer from the host panel. So, typically in a repair, it’s covered with seam sealer where you can’t identify where your welds are. First thing we need to do is remove that.

01:25 — So there’s a couple of options we have here. I choose to use the file belt with a Scotch-Brite belt. Now the reason I do that is because this will really highlight the welds. You don’t want to get overly aggressive.

01:38 — You would just want to take off enough material, and it’ll identify exactly where those welds are; it will actually show them very well.

01:46 — Some techs may choose to use a Roloc disc or some other abrasive tool. The problem with that is when you grind with an abrasive, it’ll actually disguise where the welds are, and make them more difficult to see. So my choice is this, and that’s what I’m going to use now.

02:01 — I’m going to secure this to the bench, so it’s not moving around here, and we’ll get started.

02:22 — So as you can see here with the Scotch-Brite belt, and not being overly aggressive, you can actually see the welds very, very easily. It’s almost like a guide coat where you can see the primer in the bottom of the weld.

02:35 — But if I use something too aggressive, it would erase all that indication where I wouldn’t be able to see them anymore.

02:42 — So the Scotch-Brite products work very well for removing the seam sealer. The next thing I’m going to do here is begin to grind my welds.

02:49 — I’m going to switch over to a grade 80 file belt to be able to do that. Now the most important thing in this step is that I again don’t get too aggressive.

03:02 — I’m working on thinner metal here. I want to go, and theoretically what I’m trying to do is cut and make that top layer paper-thin without going all the way through and damaging the bottom host panel.

03:12 — So we have to be careful how we do that. I actually use a count in my head to know how long to go to cut that well, without getting into that bottom panel. It’s something that you pick up over time. After you do it a few times, you’ll get the hang of it if you haven’t used that before.

03:26 — So I’m going to carefully grind those welds and remove them, and we’ll go to the next step after that.

04:19 — So now, as we can see, this came apart very nicely. I still have areas that are actually high here, where I haven’t dug into the hosts panel. And that’s the main goal here is not damaging this bottom flange. If we grind way too deep, we may actually have to replace the inner part, which you don’t want to have to do.

04:40 — Okay so the next step here is I want to grind these weld nuggets down, and I want to abrade the surface to prepare it for the adhesive. This is a great place now for that Roloc disc.

04:55 — And the reason a Roloc works better in this case, then the file belt tool, is the file belt tool can tend to put some undulations in that surface., and not make it perfectly flat, whereas this will plane it nice and flat. As you can see, it’s planed down, and you can’t see any large divots or areas where the welds were cut too far.

05:16 — So that’s what we’re looking for here, is a nice flat surface with a nice abrasive grinder mark, that’s going to allow that adhesive to bond better.

05:45 — So, what we’re looking for here is that we grind this to what we call bright steel. Now one thing you want to keep an eye out for is if you grind, and you see a dull gray color, that indicates that there’s still some galvanizing remaining on the panel.

06:00 — You don’t want that galvanizing under the bond. That would be the weak link. So, in this case, we’ve got that ground nicely to bright steel ready to prepare for our adhesive.

06:12 — The next step we’re going to take here is to clean everything up, and get ready to apply that adhesive.

06:34 —So the next thing I want to do here is prepare my replacement panel. The host panel has already been completed, ready for adhesive. Now we have to prepare this.

06:44 — So your replacement panel from the OEM is typically going to come with some E-coat on it, or some type of a primer. We want to remove any kind of coatings that are on there. And, also again, put that abrasive tooth in there that allows that adhesive to grab that surface a little bit better.

07:32 — Okay, now that our two parts are cleaned, and prepped, and ready to go. We’re ready to apply our adhesive. So I’m going to get a cartridge prepared and ready to go.

07:42 — Okay, I’ve got my cartridge here and an applicator gun. A couple things I just want to address before we mate these parts together. We want to make sure that we really have these surfaces well clean.

07:52 — One of the questions we hear all the time is about parts that may have some existing corrosion on them. So, in other words, you cut off a box side of a truck, for example, and in that wheelhouse area on the host panel, there’s heavy corrosion.

08:08 — If it’s heavily corroded, that part probably needs to be replaced. If you can’t remove all the corrosion entirely down to that bright clean steel, you should replace the part.

08:18 — This product has chemical corrosion inhibitors in it, but that will not stop or slow down existing corrosion. We want to make sure all the old adhesive, all the corrosion, any kind of contaminants are removed, and we have this nice clean steel.

08:34 — So I’m going to load this cartridge into the pneumatic gun. And I chose a pneumatic gun to show this because one of the other questions we get from techs all the time is that “How can I extend the amount of time I have to apply the adhesive, and attach, or fit the panels to the car?”

08:52 — And there’s a couple things we can do. Number one, we can keep this adhesive cool, in a cool place. On a hot day for example, and that’ll give us a little more time.

09:02 — The other thing we can do is just get it on the panel quicker. So if I’m doing a large roof panel using a hand applicator, it’s going to take me longer, and that’s going to cut down my work time. So this way I use a pneumatic applicator, it lengthens that work time that we have.

09:18 — First thing we need to do before we do this is equalize the cartridge. Always very important. Otherwise we will not get a proper mix, and it may not cure.

09:35 — So I like to equalize into a paper towel, little at a time, just so we get even amounts of material coming out. And this material is a 2-to-1 mixture, so you’re going to have twice as much of the one side as the other, which is normal.

09:52 — I’ll attach a mixed nozzle, retaining collar, and then we always want to exclude a little bit of material, couple inches or so, just to make sure we have an even mix.

10:20 — So the important thing to know about applying the adhesive, the key thing, is that we’re going to do three applications.

10:28 — So we’re going to do what I call a primer coat first on both parts, host panel and replacement panel. Then we’re going to put another bead down, which I call the squeeze-out bead. We want to spread this out, force it into the surface.

10:42 — You want to use enough adhesive that we get good squeeze-out on the panels, without overusing where it’s, you know, dripping all over the floor and making a big mess.

11:04 — So you could use a plastic spreader. You could use an acid brush. To me, an acid brush takes a lot longer to spread it all out, whereas a spreader can do it very quickly. But it’s personal preference.

11:30 — The important thing here is we want to cover all the bare metal. Leaving any bare metal exposed we’ll open it up to corrosion. Don’t just put a bead down, and expect it to squeeze out and cover all the bare metal.

11:42 — Make sure, again, this is a primer coat, where we’re covering the entire surface. Then we can put our third bead on either part, whichever is more convenient. A lot of times it’s easier to put it on the host panel, because you’re not carrying it around, but it really doesn’t matter either way. So just a good 1/8-inch to ¼-inch bead on one part.

12:17 — Now we’re about ready to mate these parts together.

12:20 — Keep in mind, there are glass beads in this product. There are 10 mill glass beads, so you really can virtually not over clamp the parts. You want to clamp them nice and tight, and keep them clamped during that clamp time. That’s very important.

12:35 — It’s also important that during that clamp time, we don’t do anything that could possibly shift those panels, like move the car, or take it off a frame rack, or something of that nature.

12:45 — Because what can happen is that as the adhesive moves from a liquid or a paste stage to a solid stage, if in that process, it separates, it will not blend or melt back together again. So you’ll have a separated area in there. So we want to do this, clamp it tight, and leave it in place during that clamping time.

13:04 — The other thing we don’t ever want to do is put the parts together, and then if something’s wrong, pull them apart. If we do need to move the parts a little bit, we can shift them by sliding, but if you pull it off, you need to reapply it, because you put air pockets in the adhesive.

13:18 — So I’m going to mate these parts together. And, it’s obviously a really good idea before we apply the adhesive to do a dry fit, and make sure everything fits, all your gaps are correct, and then mark where those areas are, where it was on the vehicle exactly, so you don’t have to refit everything when you put the adhesive on.

13:42 — So now we’re pressing these together. You can use a number of types of clamps here. I just chose these. A lot of you guys use these in the quarter panels because you can shut the door. They work really well, and these are very simple. I’m going to use these for today.

13:54 — So I’m going to clamp these down. You could use clamps like these here, you could use normal vise grips like these here. You want to clamp this down, placing your clamps maybe every 2 to 3 inches. You really don’t need to clamp any more than that.

14:18 — As you can see, I’m getting some nice squeezing out of that area. And that’s one of the big benefits of using an adhesive in the joint is that it completely seals that joint. So it seals the joint for corrosion protection, it improves noise vibration and harshness, and you have a continuous bond that’s very, very strong.

14:52 — Now that I’ve got my part clamped to the vehicle, we’re going to clean up as much adhesive as we possibly can while it’s still wet. And the reason that can be important, especially on corrosion vulnerable areas on a vehicle, is that if we wait until it cures and we grind it, now you’ve ground that edge down to bare metal, exposing bare metal.

15:12 — That may not sound like a big deal, but think about in a wheelhouse on a vehicle. And, if you grind that inside edge on that wheelhouse, it’s very difficult for the painter to get in and paint from the inside out, and get that edge covered with sufficient coatings.

15:28 — So we want to try to avoid grinding this adhesive off as much as we possibly can. There may be times where we have to. This is where the acid brush really shines here; where we can get in between our clamps.

15:40 — And that’s the difficult part. We’ve got clamps all over the place, it’s hard to get it all off, but we can get in here pretty good, between all of our clamps with our acid brush, and do a pretty good job of cleaning off that squeeze-out.

15:55 — Being neat as we can, but as we know, it’s always difficult to keep all the adhesive off everything. Which brings me to another point is that this adhesive cleans off very easily while it’s wet. Even soap and water will take it. Okay, so solvents work great as well, but soap and water does a good job.

16:13 — So now that we’ve got everything cleaned up, we could move to the next step, which on a normal vehicle would be applying any post repair foam. There may be some areas on the vehicle in a sail panel, or a rocker panel, a dogleg, where we have to apply some foams. We want to do that, and then we want to also apply our Cavity Wax.

16:33 — Now, that’s of course after we have observed the proper cure times. We have to closely observe the proper cure times to allow this adhesive to set up fully before it’s put back on the road.

16:44 — So a couple things to think about here. Number one, one of the really strong advantages of this adhesive, and being epoxy technology, is that it handles heat very well, and you can heat cure very easily. So as little as 40 minutes at 150 degrees will get you to almost full cure time.

17:04 — But observe those temperatures carefully, and realize those are the temperatures of the panel, not the ambient air in the shop. So make sure your panel gets up to that temperature for the given time. But in the instructions, you can also consult the small chart that’s in there that will show those cure times and temperatures.

17:21 —So we want to just make sure we’re observing those times before we put it back on the road to make sure it’s a safe repair.

17:28 — So that about does it for this repair. The one thing we need to consider, though, is that for this I use 8115. Now we have other options that can be used as bonding adhesive, so that’s where we want to always consult the OEM for their repair information.

17:43 —That information may vary based on year, make, model or even specific panel, so we want to consult that to identify which adhesive is specified by the OEM.

17:52 — We have another video coming up soon that is a more advanced look at this repair, where we’re gonna actually consider MIG welding and spot welding in those areas, which brings up a whole host of other topics that can get tricky, and need to be discussed.

18:12 — So you can see more of this at 3MCollision.com or visit us at 3M Collision Repair Academy. We’ll see you next time!


3M™ provides best practices for pre-fitting, cutting, panel prep and installation when following OEM recommendations for panel bonding adhesives.


This clear, easy-to-follow SOP include surface preparation, application and tooling of the seam sealer to recreate OEM appearance. It also includes important information on applying tight coats to help ensure the joints are properly sealed before tooling.

Ryan Marrinan, Application Engineer

00:13 — Alright guys, you hear us talk quite a bit when we’re referring to our seam sealers, as far as making a nice tight seal to the surface, and some of the tricks we’ve used, whether it be brush strokes, ripple beads, caterpillar beads and how we accomplish that, so that we have a good tight seal.

00:28 — This is going to help us prevent air transfer amongst the vehicle, but more importantly water and corrosion being intruded into our repair prematurely.

00:37 — As long as we’re following the proper procedures here, we shouldn’t have any problems.

00:41 — One of the things that we’re going to do here to represent that, is as you can see, I’ve laid out some beads. And what we’re trying to show you here is the importance of making sure that when we’re putting these down, that we’re actually not getting air pockets. That we’re not laying the material on the surface. That it’s actually being put into the substrate itself.

00:57 — This could be aluminum, could be steel, could be fiberglass, whatever it is that you’re working on.

01:02 — As you can see here, I have some beads laid out, and how we’re going to show you this.

01:02 — By showing you the seal that we have underneath the seam sealers, once we have them applied.

01:21 — Now, for those of you that might have questions, yes all these seam sealers are currently wet. They have not fully cured yet. We did this for a reason.

01:28 — Once they’re fully cured, we know that we’re gonna have adhesion to the surface.

01:31 — So we wanted to show you that even from the get-go, we’ve got this taken care of.

01:36 — We want you to feel comfortable using our products, as much as we want you to feel comfortable replicating OEM beads.

01:42 — Using our products and that method, put together, can ensure a proper repair each and every time.

01:48 — For more information on our seam sealers and our best practices, check out 3M Collision Repair Academy on our website. The link for that is in the description below.

01:56 — Also check out some of the other videos we have here on our page. If you hit subscribe, and the notification bell over here in the corner, that’ll keep you up to date as we’re releasing new content, new videos to keep you up on today’s best practices in the industry.

02:09 — If you guys like this video, hit the thumbs up. Also throw a comment in the section down below.

02:15 — I appreciate you watching, and we’ll see you next time.



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