[PaulatFast]

I'm hoping for some insight here, not a sales pitch. In my opinion, both of these fillers fall under the "Trick of the week" category. This category is filled with body shop goodies, self-etching primer and sprayable polyester filler come to mind.

So, someone tell me when these fillers should be used... AND why? I seriously want to learn something here, please be ready to back-up your opinion, that's why I'm asking the question. Several sales people have tried over the years... in general, they are weakly prepared to answer questions with facts, yet full of useless sales lines.

Thanks, Paul

[61-63]

I use Metal to Metal when I've stitch welded a patch in and haven't obtained complete
coverage with weldment. I put a coat of Metal to Metal, or Acraglass I think it is called, which are both waterproof, sand it down, and then put regular bondo on top of that.

Metal to Metal can supposedly handle higher temperatures than regular bondo so I will also use it to deal with imperfections in valve covers and such.

[paint guy]

Paul, I'll relate this story FWIW: A couple of years ago I was talking to someone who does what I would call "high-end" paint jobs (custom graphics and colors on both classic and late-model vehicles). I noticed his 2 Victory motorcycles with tank graphics and he told me, on a lark, he filled the scalloped metal on the tanks to have a flat surface for the graphics. Victory tanks have a scallop that is probably about 3/4"-1" deep. He said he filled them figuring it would last a year or two, but he figured this would be a good test, being on motorcycles (his and his wifes), and when they cracked, he would either buy new custom tanks or weld in panels over the scallops. When I saw them they were going on about 6 years, according to him, and hadn't cracked yet. I beleive he used "Metal-to-metal", but it could have been "all-Metal", I can't be sure. ( I am NOT suggesting, and neither was he suggesting to apply any type of filler at a thickness anywhere near approaching an inch) But he was convincing enough to me where I have used Metal-to-metal on a quarter (over a weld) on an 08 Impala about 50k ago, and that hasn't cracked yet. I would not hesistate to use it in an area that was previously leaded, like a sail panel joint, or an area where I needed extreme moisture control. I don't know this, but I think it is very similar to regular filler, except some of the inert filler pigments have been replaced with aluminum flakes. It can be somewhat tougher to sand than regular filler, but not as hard as "tiger hair'. On the other hand, you obviously have your procedures and products down, and you know what works for you, so you may never have a need to use it. just my .02.

[pfilean]

There's an old fellow here in town that I use occasionally to make patch panels for things where I can't buy one and am not good enough or have enough equipment to make my own. Interesting guy and nice to talk with when I get to his place. He has been doing this for years and used to have a body shop although now he just works with his son in a fire wood heated garage and does restoration on old suff that comes in the door. A while back he virtually made a WWII command car from scratch as the body that came in was severly rusted.

Anyway, in some of the conversations, he said that he had never had a call back from filler re-rusting out since he started using All-Metal as the first filler layer. I have seen filler put in by the "anybody can patch rust" guys rust out or bubble through the paint after a couple of years. So I figured if All-metal is good enough for the old guy I'd try it. Haven't had any problems although maybe not enough years have passed for things to deteriorate again. But the story is that the binder in the filler will not absorb water and transfer it through nor allow it to rust the bond line to the base metal. Actually my supplier carries Metal-to-Metal but I think it is about the same stuff.

[jetallman]

Good thread, I'm getting ready to do my new quarters where I removed the lead and I am reading this with great interest, but at this point it has been a 50/50 for both as far as I can tell

[PaulatFast]

I've never had an issue with regular filler that I know of. But we don't spread it very thick, rarely over an 1/8" thick. We always fully weld our patches. We always fully weld the factory seams, grind the welds and fit/weld a patch over them. So I'm not seeing any benefit we'd gain from using it. So for something like filling a factory lapped seam, if not welded and plated, the all-metal type of stuff may be beneficial. Or applying over a patch panel that is stitched on instead of butt-welded... Or when scupting panels...

So, the added expense doesn't seam justified in my case.

It is interesting to me that those other uses listed would have been places I would have used fiberglass filler years ago. It sounds like these fillers are a modern upgrade to the old fiberglass stuff... is it more water-proof than the fiberglass?

[PaulatFast]

Forgot to thank you guys that responded. It's what I'm looking for. Hope there are more responses. I already have more insight than I've ever had before!

[61-63]

The two benefits of the Metal to Metal, to me, over the fiberglass filler, are 1. it sands easier after it sets up (sanding on the fiberglass after it sets up is like sanding on concrete), and 2. it will take heat so it is OK on engine components. The one thing I don't like about it and someone mentioned this, is that the catalyst is clear and you can't tell you've mixed it into the paste well.

[niceta]

I am no expert and don't claim to be but I was told by an ex body man of 15 years to use "all metal" or a fiberglass type filler for covering my but welds for a couple reasons.
1) strenthens the welded area
2) does not (less prone to) absorb moisture. In case there are small pinholes missed by welding moisture can enter from backside
3) can "help" prevent a pitted/previously surface rusted area from further oxidation/rusting by sealing it from moisture/air.

This being said if I were in buisiness of repairing cars for a living I would use All metal sparingly as it is very expensive. It does apply very nicely and sands easily as well if sanded before it cures fully. Better have some good quality sandpaper though.

[Greg Reid]

I've used both Metal 2 Metal and All Metal. I used it at the lead seam at the A pillar to roof joint. I also used it over every patch panel weld seam I've ever done...I'm a novice welder/body guy that's going to have a pinhole here and there.
Good to hear that people have had good results with this.
I'd like to point out that I've noticed quite a bit of difference in the two products..
In my experience, the All Metal is much harder to sand and get a smooth finish on than the Metal 2 Metal. The M2M sands about the same as Rage or Bondo. Very smooth.
What that means in the long run, I don't claim to know....Maybe the All Metal is better for sealing purposes? More metal content maybe?
I always used Rage or some other body filler over the All Metal for a smooth finish. Using the Metal 2 Metal, I found there was no need. In fact, after sanding, it looks like grey primer. The All Metal, looks like metal no matter what...but I'll admit, I didn't sand it too much. It's tough.
I would rate either one superior to the fiberglass impregnated type filler that I tried once for ease of sanding and finished appearance.
Disclaimer- The appearance aspect is probably pschycological....they just look like metal when you spread them on, as opposed to that dark green, glossy plastic looking fiberglass filler I tried.

[Greg Reid]

One other item. Someone mentioned the clear catalyst...Metal 2 Metal has a clear catalyst but the All Metal has a reddish-brown catalyst.

[First Bird]

The guys at my local paint shop recommended All-Metal for first filler on my quarter panel and tail panel welds. Glad I did. You can just tell when you put it on that it will protect those welds.

[70 Rick]

Nobody has mentioned this yet so I will, it doesn't shrink like other fillers either. I used it instead of lead on a quarter to roof seam on my GTO almost 15 years ago. No shrinkage or cracks at all. It's not snake oil, the stuff works.

[PaulatFast]

The premium fillers don't shrink either... I don't think Fiberglass fillers shink after the initial curing process...