Filler to bare metal causing metal to sweat ! What

All good points, many good reasons to seal with epoxy first, i say even worth it on collision jobs when it's justified!
 
Chad.... You are definately right. If I had my own shop, and had the choice, that is the way I would go. Working for someone else, you have to play by their rules. Where I work now I don't touch primer. The painter sprays the primer and blocks it, if needed, before painting.

Aaron
 
Epoxy under filler is also recognized by I-Car as a best practice. I'll see if I can find the literature.
 
Here is all that needs to be said about every six years, when these INTERNET bogus tests and testimonials show up, saying the same thing but with a newer date.

WHY? If you are doing warranty work on the following cars, they require epoxy under the repair?

Mercedes (started this back in early 80's, was the first)
+The company they hired for am recommendation was BASF and as i understand did 3-4 years of testing before making this recommendation.

Porsche.
VW
Audi
Land Rover (aluminum bodies)
Toyota

There may be more as I have not kept up but what do these people know that the INTERNET wonders that write this stuff don't know and in all fairness, do know?
 
To me just the logic of having the metal sealed from exposure to moisture makes the case. We know filler absorbs moisture so having a protective layer of epoxy between the metal and filler just makes sense. I realize some try to argue the adhesion issue but if the car is subjected to the same metal pounding, flexing in these tests you will be replacing/repairing the panels anyway.
Another nice thing about epoxy under and over the filler is the filler itself in now sealed from moisture and potential deterioration.
 
To me just the logic of having the metal sealed from exposure to moisture makes the case.
Click to expand...
^ this. depends on environment too, if the car is garaged, what the climates are, salt on the road, etc. i prefer epoxy first when im filling a ding on a harley tank..
 
Very good supporting info on epoxy under filler. If filler came off as a result of body damage it's a moot point it damaged anyway.
 
Salt is no issue here. Done it both ways so I won't put any one down no matter what they choose. Good points all around. When is too much? One thread they seemed to have 10 or more coats (I lost count) of epoxy on a car? How do you know you have too much?
 
When the procedure is done properly and testing is done after full cure the epoxy under filler results always perform better both in bend testing, adhesion, and corrosion resistance. Not everyone has the time allowance or feels it's important enough to do it regularly but when someone puts up an argument against it I feel obligated to speak my mind. I've tracked how this proceedure has performed since the late 80's when PPG was popularizing it and it's made a big difference on how long my work has lasted. The time to do it properly isn't a big sacrifice when you realize how much better the repair is. And when you spend hours upon hours undoing bad repairs others have done on these old cars you really get a good perception of what doesn't last.

Have you ever seen bubbling failures when people apply fillers over braze? -doesn't happen when epoxy is put down first

Worried about the strength of adhesion the epoxy offers? - note it's I-Car recomended for proper glass setting-think airbag deflection, also many adhesives require epoxy primer over bare metal.

Do you worry about the bond strength of primer surfacers or paint over epoxy-just try to seperate that bond...

Want to use polyester products on SMC and know the bond is adequate?-put epoxy primer down first.

Worried the plastic that bumper cover is made of won't accept the flexible polyester filler material you want to use?- apply epoxy primer first
 
I think most shops that resist using epoxy first are more concerned about production than quality.
Filler first iis one less step, less cure time, and you don't need to worry about sanding through. All the other arguements for using filler first are just a facade.
 
Yes Strum.... The management in production shops spend all their time trying to figure out how to get the cars thru faster and cheaper. The insurance companies have formulas that they use to determine how long they will pay for a rental car while a car is in the shop. Nothing in that formula figures time for letting epoxy even start to cure. It is not unusual to get a car in today that has to be repaired, painted, and go home tomorrow.

Aaron
 
Customers usually demand quick service, look at the parts order timeline nowadays. I remember when you were happy if the parts came in a week after the order was placed, now people are upset if it takes a few days.
 
Bob Hollinshead;16121 said:
Filler over bare metal- It's a time tested proceedure that will fail in road salt country if the paint surface is ever compromised-rock chip...
Click to expand...

LOL-If you get salt or moisture past your paint and through your filler, all the
way to the metal, you need to replace all of it, wether it's on epoxy or not.
 
Body fillers contain talc, talc, as used in baby powder absorbs moisture. Unless you have a "specialty filler", a conventional body filler will absorb moisture. As far as condensation occuring between bare metal and body filler, I don't think that's an issue. The only time it would be an issue is if metal temperature is too low,(pulling a car in during winter months and not allowing it to warm up) then you could have a problem. Body filler mixed with hardener performs at catalytic reaction, creating heat, which could cause condensation IF the metal was cold. I-CAR does support epoxy over bare steel prior to body filler application.
 
jcclark;16245 said:
LOL-If you get salt or moisture past your paint and through your filler, all the
way to the metal, you need to replace all of it, wether it's on epoxy or not.
Click to expand...

yup, if the damage goes to bare metal rust will form-LOL, common sense.... but if the scratch or chip is only through the paint the job will last just fine if epoxy was used as a base. Add filler to the scenerio and it acts like a sponge holding moisture and the corrosion will ramp up very fast unless there's epoxy below. I don't know what's so hard to understand. Think about it... Body Filler doesn't offer much corrosion protection.
 
"You're putting the horse before the cart"
If moisture gets through the paint by way of a chip or hole, the filler is going to get
wet wether there's epoxy on the metal underneath or not.
It will fail, the filler & paint will need to be replaced,
The epoxy on the metal underneath doesn't protect the filler, that's the weak link.
I've been putting filler over bare metal for over 30 yrs and never had a failure yet,
if one does fail, it'll be because of a hole in either the metal behind it, or a opening in
the paint above it, either way, the epoxy won't prevent that.
Epoxy IS a better way I'm sure, it's just a moot point in the real world.
Either way, the repair will far outlast the car when done right so
keeping the customers car another day just for the epoxy underneath to
dry before applying filler really isn't worth it, not on the collision repairs I do.
 
I undid an old repair tonight where there was rust bubbling filler, the person who applied the filler trapped some air which caused the corrosion to start, had he put down some epoxy first the corrosion would have never started. To each his own.
 
with collision work it doesn't matter. the car will most likely be sold in a short time anyway. but those of us doing high end work have to follow a different set of rules. and rule #1 is epoxy first . period . and there is moisture in air which can get trapped when applying mud. popping off a chunk of bondo and seeing a ring of rust is nothing new. pick the wrong day and you set it up to fail .
 
Here is what Brian Martin said about Evercoat's opinion on the subject (I don't mean to say Brian is for sure the expert he professes to be-- LOL-- but he does know the questions to ask) 1-15-2012 Hotrodders.com

"Yes filler does bond chemically with epoxy and the reason the manufacturers of fillers don't recommend it (which they DO in a certain back handed way) because they can't recommend using their filler over EVERY epoxy ever made. Now, if they can't recommend it over EVERY epoxy ever made which ones are they going to alienate by calling names? Their products are sold in stores that sell paint, which paint companies are they going to tick off and throw their fillers out on the sidewalk? I had this told to me by a guy in the tech department at Evercoat standing next to their booth at NACE. Now, if you read their recommendations every product in their "Metalworks" system has a recommendation for applying it over OEM paint and primers. Just how does it "Chemically bond" with the paint and not an epoxy primer.

And Evercoat DOES NOT recommend 36 grit ground metal. 80 grit is the coarsest grit recommended for ANY step of the filler by Evercoat."

Brian

So if the paint manufacturers, luxury car manufacturers, I car, and probably Evercoat all recommend epoxy first, then why would you doubt it?
Yes, filler has been put over bare metal for 60 years, but epoxy wasn't available back then.
 
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