http://www.stuart.iit.edu/students/2.../paintprep.htm

Does this person know what they're talking about? Is bondo bad?

 

Moving to Body...

 

Bondo is good as long as the prep work is done right, and the application of the bondo itself is done right. IE: don't apply it in 1/4" thick amounts, LOL.

As far as bondo absorbing water, yea ...it does, if you don't paint over it. After primer, primer sealer, paint, and clearcoat, there should be no water going through your paint.

 

Still, when possible is it better to avoid bondo and other fillers?

I mean...I have no idea how it works, if they can smooth it out by hand and just fill low spots with sanding/primer. I plan on having all the damaged body panels replaced. I dunno, I mean, other then my door/fender/bumper...the rest of the body is straight, I have like, 1 or 2 little tiny dings on my driver door, would it be wiser to let them knock the ding out (they would still use bond probably right? No way to make it "perfectly" flat without some filler to sand down? Or should I just have them rip off the driver door skin as well and weld on a new one, cause my passenger one got hit....and that ones gonna come off. I don't care if it costs more, I just want it done right and to last.

 

Even new door skins might have a slight wave to them. My brand new quarter panels (both sides) needed some light skims of bondo to make them completely straight.

As for your doors, like you said...try and knock the ding out as best you can, and then you'll need to use putty or a small amount of bondo to make it flat.

Ain't nothing wrong with bondo

 

So that guys post I quoted is somewhat misinformed....as long as the bondo is sealed and never sees water it should be fine?

 

As long as you seal the bondo from the elements of weather and do the proper prep work then you wont have to worry.

 

yup.. like they said.. actually you'd be surprised even some of the new cars I've seen that had never been into a body shop.. had some bondo or putty on them..

 

What is that?

 

when they assemble the cars at the assembly plants.....some of the parts might actually hit other parts going down the assembly line....get little dings here and there in'em....so...they have to slap a little filler in there. Like every else has stated...if it's prepped right.....bondo is good

 

Bondo is absolutely necessary in 99% of body work. If it's done properly, it'll outlast the metal around it.

Bondo only bubbles when some idiot used it to cover up rust without completely removing the rust first. As the rust comes back, it forces the bondo to bubble. People think grinding out the rust is sufficient... it isn't. You need to sandblast or use a quality chemical treatment.

 

As for the dings, they can be removed by a dent person. If they are minor door dings, they can be removed, leaving the panel perfectly flat. A good dent guy can make it look good as new.

On the front fender of Camaros, there is usually a low spot and a high spot associated with the 3 body lines coming together. These lines are the wheel well lip, the wheel well contour and the mid body bodyline. When these body lines are made, they create a slight wave in the metal. I have removed these waves on a few Camaros and made the fender look flat and smooth. Never use bondo if you don't have to. Contact your local Paintless Dent Removal guy for the dings.

 

and for you custom guys out there.....don't you just love bondo? haha....I wouldn't have been able to shave my antenna without it...some other things like...door handles, locks, gas doors..etc....

 

correct me if i'm wrong, but i've heard that on the real custom show cars, they cover the whole car in a real light coat of bondo, that way they can sand it perfectly straight and cut all the door gaps so they are perfect. like everyone has already said, if bondo is done correctly, you would never know it's there and it will last a long time.

 

You're right.

The correct way to shave a panel is to fill the void with metal. The pros usually weld in a piece of metal to fit the shape, grind it smooth, then they will sometimes lightly skim over the whole car with a very thin layer of bondo. This fills in any voids in the metal and allows for a perfectly smooth surface for the paint.

 

skim over the WHOLE CAR? i would think that that would mean the first minor ding would crack the bondo and it would eventually start to spread over the car? i got my 1/4 dinged in a parking lot insurance gave me $1000, which is all going into my motor. and im afraid ill have to use some bondo on my fender before i paint it. is it ok to get more than 1/4'' if you layer it? i was thinking of drilling some holes in the metal and forcing the bondo to "ooze" out the other side, that would give it a better hold right?
ideas?

 

a thin layer is so thin, it's transparent. It fills the minor scratches in the metal and the remaining is just about enough to sand out. The way you want to do it will allow it to crack.

 

the idea isn't to put a thick layer on, it's just enough to fill in any minor imperfections in the metal. if you have a dent that is gonna take more than 1/4" of mud, i was advise you to get the dent pulled as much as possible. you don't want to fill a dent with bondo, you want to pull the dent out and fill the imperfections that dent created with bondo. there's a big difference.

 

theoretically metal should be pulled out to within 1/8 of its original shape before bondo is used, according to i-car. but sometimes that impossible due to severe damage to a panel. one thing to consider also is for bondo to adhere to a panel ALL PAINT MUST BE REMOVED not scuffed a little. bondo is also not very flexible, if all you want to do is fill dings use a polyester putty instead. its more flexible, creates less pinholes, and can be applied to sanded panels.

 

That was another issue, that if a bodyshop uses bondo, if I get tapped by a door or it gets a ding, the bondo will crack. Though it appears even if I do get all new panels, I'm still going to need bondo done.

Will a body shop know to use puddy and not bondo to fix door dings?

 

any competent shop should know when to use what product. if you have any questions ask them what their repair procedures are. the only way bondo cracks is if its way to thick or if it gets hit hard enough (in which case you probably wont worry about a little cracking bondo anyway as youll probably need new panels).
i personally have no problems with using bond on my vehicles.

 

I agree that body filler is required in most body applications. Make sure to use a quality filler and not "bondo". Ask your local supply store for a quality catalyzed filler. A quality filler can be used to fill low spots, mask factory stamping distortion, blending panel skins..etc with little to know worry if it's applied properly.