DIY How To Bondo Auto Body Repair (Tips and Tricks) To Prevent Common Problems with Body Filler

(upbeat music) – Hey, this is Donnie Smith. Have you ever overground metal, making it too weak and too thin? Well it’s not that hard to do with these thinner metals. What about when working with body filler? Have you ever gotten it in cracks, gaps, other places
that you don’t want it? Takes quite a bit of time to get that out of there and clean it up. So if you’d like to learn some tricks, how to prevent over-thinning your metal when working with thin metal, and how to keep from
getting all the body filler in the places you don’t
want it in the first place, then you’re in luck, because that’s what we’re
gonna show you in this video. Alright, let’s just go
ahead and get started. What we’re gonna do to eliminate grinding a lot of the metal off,
is to use a DA Sander, and we can use 36 grit, or 80. I’m using 80 here. That usually works well. May take just a little bit longer to remove the paint coatings, but you’re not gonna chance
grinding too much metal off. This does not take the amount
of metal that grinding does. Now with thinner metals,
I would recommend this. Now if you’re working on older vehicles, grinding may be a little quicker, and that may still work fine. Okay, now for the tip of how to eliminate getting body filler in places you don’t want it, and that’s simply to mask it off. On the edge, I don’t want the body filler wrapping around the edge
where I have to clean it up, so I’m gonna mask that off. Any gaps, for instance here, there’s a, where the molding goes, I don’t want body filler to wrap in there where I’m gonna have to sand it out, so I’m gonna use the body
lines that’s on the car, and use that as a dividing line to make nice, sharp lines at, so that the body filler
does not get in these areas. (upbeat music) Okay, now I’m mixing the
body filler up in the tube. I’m gonna let the air out of the cap, so that it’ll mix well. And once I remove some of the air, I’ll put the cap back on, and now I’m just gonna
mix it inside the tube, because this hardener really
does separate a lot in there. If you don’t do this, you’ll have liquid-y
substance that comes out, and you don’t want that, so be sure that you mix
it up well in the tube before you use it. Now I’ve already got some
body filler out here, and I used a paint stick to
put some on this mixing board. And I’m gonna get this hardener, I’m gonna apply a strip
from edge of the body filler to the other, and that usually is a pretty good mixing ratio. And notice I’m using a spreader to mix it. I’m not using a paint stick to stir it, because that could put air bubbles in it. If you get air bubbles
in your body filler, that’s gonna create pinholes, whenever you go to sanding body filler. So it’s always best to
work the air bubbles out. Just spread it out on your filler until it’s nice and uniform. You don’t want there to
be any hardener streaks. You wanna mix it until it’s one color. (upbeat music) Okay, now I have the filler mixed good. It’s nice, uniform, one color. We don’t have any hardener streaks in it, so we know that it’s mixed well. I’m gonna apply the body filler. Now to do this, I’m gonna
apply a tight coat first, and what that is, is
where I take a thin coat of body filler, and push really hard down on the spreader, so that
I push it into the metal. That helps it adhere better to the metal, so that you don’t have any problems with adhesion at a later point. Now once I get the tight coat on, I come back with a fill coat, and that’s where I’m gonna
put a little bit less pressure on the spreader, which allows it to fill the damaged area in. (upbeat music) Okay I have the fill coat applied. Now here’s a tip for you to eliminate a lot of the sanding, and that is to work on your edges, because if you have real hard edges, it’s gonna take more sanding. So what I’m doing here, is I’m using the spreader, and on the edges I’m kind of feathering that body filler out, so that edge is a real thin layer, and you don’t have that big, hard edge to try to sand out. Okay, now let this set
up for just a little bit, and you don’t want to do it immediately after you apply the body filler. You wanna let the filler set, but you don’t want it to be dry either. But as it’s kind of in its green state, go ahead and pull the tape off. This will leave you nice clean edges. And also before it fully cures, you can block sand lightly, you don’t wanna sand too hard, just to help level some
of the highs and lows. Okay, now I allow it to dry, and started block sanding it. Now I’m starting out with 36 grit, because that’s gonna level
the filler really fast, but notice that I’m
staying within the filler. My block is not sliding
out onto the paint, because I don’t want those deep scratches getting onto the paint surface. I’m just wanting to level the filler. (upbeat music) Also notice that I’m sanding
in different directions. I’m not just going at one
angle the entire time. So I change it up. And what sanding in
different directions does, is it’s gonna help you
get a more level surface. So always sand in different directions. (upbeat music) (sanding) (upbeat music) Once you have it level, switch to 80 grit. That’s what I’m doing here. First, I’m gonna apply some guide coat, and this just to help
identify highs and lows, and you’ll know whenever you get rid of the 36 grit scratches. Makes it easier to see this way. Now also notice I am sanding
out on the paint a little bit. I’m not going too far, but you do wanna sand out further than you did with your 36 grit. You wanna make sure all 36 grit scratches are removed during this step. (upbeat music) Okay I finished blocking, and I’m feeling for high areas. And usually if you see
metal spot areas like this, that’s gonna indicate that it is high. And that happens sometimes, and if it does, what you need to do is get your pick hammer, and lightly tap down on those metal areas. And what this is gonna do, is it’s gonna lower that metal. (upbeat music) And here’s another tip for you. If you’re having problems
filling the bodywork, and determining highs and lows with your hand, with your bare hand, use something like this, a wipe all, or a towel or something
to put between the panel and your hand. And this may help you be able to feel the highs and
the lows much better. Now I’m gonna use the tape, because I’m gonna be applying some putty, so I’m gonna do the same thing
I did with the body filler, the edges, and that indention where the body side molding goes. I’m gonna tape all that off, to keep all the filler out of that. Now when using putty, it lays out a little
thinner than body filler, so I usually just go halfway, rather than from one edge
of the filler to the other. So I’m gonna do about half
the amount of hardener. (upbeat music) But everything else is basically the same. Mix it until it’s one uniform color. Don’t want any streaks in there. And the good thing about
putty is it’s thinner, and it’s easier to get a nice skim coat, but you do wanna do the tight coat, followed by a fill coat. And another thing about a putty, is you can go over the entire repair area, from paint edge to paint edge, and that helps any imperfections you had in your sanding flaws, or sanding scratches,
or anything like that, it’s gonna fill in. (upbeat music) And after allowing it to
setup for a few minutes, now I’m gonna peel the tape. (upbeat music) Now when sanding finish putty, I’m not gonna start out with 36 grit. I’m gonna start out with
the 80 to level it out. And also I wanna let it fully dry. I really don’t wanna try to sand putty in its green state, so I’ll
allow it to dry all the way. Then I’m gonna get 80 on a block, and I’m gonna sand it. And I’m gonna cross sand it. Make sure it’s good and level. (upbeat music) Once I have it leveled with 80, I’m gonna use the guide coat, and then I’m gonna come
back with 150 to 180. I’m using 150 here I believe, but anywhere between 180
and 150 will work fine for smoothing out your 80 grit scratches. And this guide coat, it will help you identify any lows that you may have if there are any, or let you know whenever you got all the 80 grit scratches sanded out. (upbeat music) And one last thing you wanna do, before you send it off
to start priming it, you wanna make sure it fits. Make sure everything aligns. Make sure that your body work is right. So you’re gonna have to
put it up to the car, and make sure everything works. (upbeat music) Always, thanks for watching this video. Be sure and share it with your friends. Give us a thumbs up, a like, and be sure to subscribe to our channel. Also be sure to go to And there we have hours of free autobody and paint
training videos like this one, and a lot of other resources for you. Thanks again for watching. Have a safe and productive week, and we’ll see you in the next video. (upbeat music)

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