Bondo vs. Lead or tin

[GSpreeman]

For dents and such that can't be removed by a paintless dent shop, I would like to deal with them myself. What are the drawbacks to using bondo vs. lead or tin? On that note, I've used bondo before but have never played with lead. Does anyone have good instructions on the application of lead?

[Formerly Steve Wilkinson]

What do you mean by a dent that "can't be removed"? the worst posible body-repair technique is the use of Bondo or any other filler. It's at the extreme other end of the spectrum from returning the metal to its original shape and condition, which is sometimes difficult but vastly better.

Stephan

[YTNUKLR]

Go into Willhoit 356 Restoration and look in their "Articles" section. I think they have an ad on how they do bodywork with "lead," and what type of metal filler is used. Good luck.

[72 four door]

Bondo can be used with great results but must be used, not abused. Shaping medal back to it original form is the ultimate outcome but a small amount of bondo/puttycoat,is needed for a completed job. If you use bondo to fill a hole more than a 1/4 deep your asking for trouble. You dont want to apply bondo over paint you have to grind the surrounding area but first bringing the dent/massaging the medal to a close level to the existing medal is the first order of buisness. Even if you used lead you would still have to use a small amount of filler.High build primerand then sand /sand / sand. IMHO

[89911]

Bondo (generic name) use has been given an undeserved bad name. Almost any custom body shop uses it. I recently saw a show on custom choppers that they custom made all the pieces. Prior to painting they all got a coating of, yes, bondo. These are $75,000 bikes also.

[Formerly Steve Wilkinson]

I have no problem with Bondo and use it myself. What I do have a problem with is sculpting a shape on top of malformed metal by using Bondo. Bondo should be employed to smooth out the final, smallest deviations from smoothness that you can achieve by trying to return the metal to its original shape and condition. Most ordinary bodyshops don't bother with this, because it's hard to do. They simply slather on the Bondo and sand it to shape. Besides, the stuff is heavy.

Stephan

[widebody911]

1/16"

Originally posted by Paul Andersen
If you use bondo to fill a hole more than a 1/4 deep your asking for trouble.

[GSpreeman]

Maybe that explains the cracks in my hood where aparently there was some dings so, one of the POs dented it in farther and then put bondo on top. Max depth of the dent filled with bondo...3/8"!!!!!!!!!!!!!!!!!!!

[Zeke]

Originally posted by GSpreeman
Maybe that explains the cracks in my hood where aparently there was some dings so, one of the POs dented it in farther and then put bondo on top. Max depth of the dent filled with bondo...3/8"!!!!!!!!!!!!!!!!!!!

Well, that's plainly a criminal act. You might throw the hood away in favor of another good one.

On Bondo: The early plastic auto body fillers were not made with flexable resin as they are today. A liilte body flex and the stuff cracked. That coupled with misuse and abuse as mentioned gave "bondo" a bad name. Today's flexable, easy sand body filler is a much improved product and you don't have to be afraid to use it correctly.

Lead is difficult to work with and highly toxic. I have worked with lead just to see how it goes. One thing lead will do, though, is fill a little deeper should it be absolutely necessary. It was used over welded body seams in new car production before WWII and into the 50's, maybe later in some cases. For purists, it is necessary to use lead on these cars. I believe there are a couple of leaded seams on 911s of some years. Someone else maybe can verify which years and models those are.

[Oliver911]

"Bondo" or plastic filler is a very generic term as there are many different types all of which are vastly superior to lead. Fiberglass reinforced filler can be used to fill deep imperfections, is it the preferred method?, No, but necessary in some situations. Standard lightweight plastic filler such as Evercoat Z-Grip, or 3M Zebra are the high quality versions of "Bondo." They are used to fill minor imperfections up to around 1/8". Finally, polyester finishing putty, such as USC Icing, is used as a fine skim coat to fill in the pinholes left by the other plastic fillers and very shallow dents and dings. The metal should always be worked until the point where the smallest amount of filler is needed, but where many people go wrong is they tap out the dent stretching the metal until it becomes a high spot, then wonder why they can't get the surface right.

Here is an excerpt on filler that is from another board and is a great explanation :

Plastic filler basics;

What ever tools you use the trick is to not add the last "skim coat' till you KNOW that it is all you need. Don't try to block out that first coat, just use it as a base for the LAST skim coat.

I was taught this procedure after doing bodywork for a number of years and it really works well:

Just apply a nice coat of filler (what ever brand, whatever style, we will put that aside right now). Cut that coat NOT to make it perfect, but to get the basic shape and filling you need as a base for the skim coat. You can cut it with 36 40 or 80 depending on how big the area you are working is. In other words, if you can cut it fast with only 80 then do it. But I would say that this would be limited to an application that is no larger than about 8 inches.

If you happen to have a few high spots, see if you can tap them down.
If you have a few low spots add a bit more filler to ONLY those spots.

Re-cut these last low spots you have just filled with the same grit you have been using (most likely 36).

If you now have a surface that ONE skim coat will fill, then apply it. If you don't work with it a bit more, but NEVER add a little here or there and think you will finish it without a skim coat.

If you have a surface that is very close with only a few VERY MINOR low spots like poor feathering onto the metal, poor transitions from one application of filler to another, or from the metal that is "poking" up here and there you can do the LAST skim coat.

This skim coat is very important, you want it to extend over the COMPLETE area, this is well past the damage you have been working. Maybe as much as 3 inches past the plastic that you have applied to "rough" it out.

This skim coat can be regular filler or a polyester glaze like "Icing" or "Polyester glazing putty", that is your choice, I use both depending on the size of the area being worked. Do not use anything that doesn’t mix with a hardener. NO, “Spot putty” in a tube, only polyester putties or fillers. If it uses a hardener, it cures to a hard film. The “spot putties” stay soft and can become even softer when the solvent from the primer coats it.

You now run a block, long board, or hog even over this skim coat with a little bit coarser paper than you plan on finishing with to cut off the resin that has surfaced in the filler. I usually just use the 36 or 40 or whatever I have been on the "rough" work. BUT take CAUTION not to cut much off, you want to JUST take the very top, don't really sand AT ALL.

Now finish sanding with your longboard or block or hog or whatever using the finer paper like 80 on a large area or 120 on that small 8" sized area. Block it out to perfection with a nice feather edge to the surrounding metal.

I can't stress enough, the trick is to know when just ONE LAST skim coat will do the job. And apply it COMPLETELY over the surface. If you only one little low spot in the middle, DON'T just do it, skim the ENTIRE thing. You HAVE to have one LAST skim coat over the ENTIRE thing every time. If you get in the habit of this you will do it over and over on every dent you repair and find that you can do just about any dent with just
two applications.

As you sand the filler let the board or block you are using run over the surrounding metal. If you only work on the filler you will sand it too low. You need to keep it as high as the surrounding metal, so use the metal as sort of a straight edge that you run the block or board off of.

Don’t worry if you cut through this skim coat here and there. In fact, you WILL most likely cut through. The point of that "LAST SKIM COAT" is that after you add it, you don't add ANY MORE filler. That "LAST SKIM COAT" is just that the LAST filler you add. If you hit a little filler below, or metal, that is normal and fine. The only thing you are looking for at that point is if the panel is FLAT. The filler skim coat is serving no other purpose than to finish you filler work, it is not a "sealer" or anything like that.

You can add fiberglass resin (“A” coat if you have a choice) adding the resin was exactly how I learned from the great Emery Robinson (my personal hero in the auto body world). But remember there was no products like polyester putties back then. When you add resin, that resin comes to the top of the film of filler. It is then something you have to deal with. The whole purpose of the SKIM COAT is to put a layer of filler over the top that is easy to block out with as little effort as possible. You want to be able to concentrate on making the panel FLAT not fighting with gummy resin, sand scratches and the like.

So the polyester putty though expensive is what I use.

How is this for an idea, a co-worker of mine showed me this very obvious tip.

Add pour-able polyester putty to the regular filler! What an idea! LOL A little pour-able squirted into the "bondo" really thins it out nicely.

The "LAST SKIM COAT" should be left to cure a good long time. Where you may jump on filler and sand it as soon as it is hard, the skim coat should be GOOD AND CURED for an hour or more. If you can of course, in the production shop you may not be able to wait that long. The benefits of the procedure will not be diminished.

A little added note, I have found that I don’t use 36 or 40 grit at all anymore. I went to work at a shop that didn’t use the coarser grits so I had to learn not to also. I have found that using just the 80 and then finishing the Skim coat in 120 or 180 works great, even on large panels.

At this shop it was the first time that I wasn’t doing my own primer work. This meant that I couldn’t “cheat” with a lot of primer and blocking the body work “one more time”. I found that I had to get the work PERFECT, then give it to the painter. I did this in an interesting way, I look at the last skim coat as even a more “final” step. I now look it as “primer”. You see I have used polyester primer, which is like spraying “bondo”. They are both polyester resin based and act and sand very much the same. So, I figured why not just “spread out my primer” as the skim coat! It has worked GREAT, the painter jokingly says, “do you think I’ll need to prime this or just paint it?” I tell him, “Just clear it, it’s a shame to hide that work under primer”.

This method has worked great for me, it’s more of a state of mind than a procedure.

And don’t be afraid to buy the best sand paper and use a lot of it, the cost of the paper will be nothing next to the time and muscles saved. Find the paint store in town that services the PROS the Body shops in town, that is were you will get the right stuff and the right info.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>“Basics of bondo types”

"Regular" polyester body filler, and polyester "putty" is basically the same thing. They are both, you guessed it "Polyester" based. Polyester is what fiberglass is made of. The fillers have talc and some other components that give it "body", that is the basic difference between fiberglass resin and polyester body fillers.
The Putties have a finer ground talc than "regular" filler. They cost MUCH more, but are well worth it for skim coats and minor repairs. Being they are polyester they use a hardener and CURE like fiberglass.
The old "spot putties" DO NOT use a hardener and are simply lacquer primer . They are JUNK and should not be used.

Some examples of these products are as follows.

"Regular" polyester body fillers:
Evercoats RAGE or "Lite weight" and others.
3M's Lightweight body filler #058001

Polyester putties:
Evercoat's "Polyester glazing putty", "Easy sand" and others.
3M's "Flowable finishing putty"#05824 or "Piranha"#05821 .

"Spot putty" (junk, not recommended) Usually found in a toothpaste tube looking container.
Evercoat's "Ever-glaze" #403
3M's "Acryl-green" red or blue #05960,05964,05966
Dupont’s 2286S, PPG’s DFL17

I personally recommend Evercoat products.

There are other specialty products that are metal and fiberglass reinforced also, but that is another "Basics".

[Harlan Chinn]

Proper lead work is expensive and not used by the majority of body shops. You would find metal fabricators and lead fillers primarily at restoration shops and you will probably pay the $$$. Current body fillers are prefectly acceptable to use once the body panel has been worked to a profile close to it's original profile. What you don't want to see are heavy or thick applications of filler greater than 1/16th of an inch.