OK,
I've seen this discussed a thousand times. and was going to do epoxy to bare metal then fill then re-epoxy but this test has drastically changed my mind. You got to check this out: http://www.autobodystore.com/filler_&_epoxy.htm
Let me know you opinions on this.

In my opinion, the reason the epoxy failed as easily as it did in the test was because of the lack of metal treatment prior to epoxy application. PPG's tech sheet on epoxy clearly states that adhesion will be increased by the use of a metal tretment (NOT self-etch). It's a step that gets skipped a lot, I even see the pros here recommending it be skipped. This is a bad thing!

In order to be a valid test the test would need to be repeated several times by some different people in order to see if that is true..One guy may get a result but then it needs to be repeated by others to get the straight scoop..

OMT

__________________
I would rather make it work than make it popular..And if it does not work it will not be popular..

The test was no good.

Maximum adhesion to the epoxy will not be until 7 days.

The test was wrong and no good.
OK to tell him I said so.

Also let it be known he had a agenda to fail the test if you read his writings in the past.

He must think he know more than Toyota, Mercedes and Porsche and VWand Audi engineers.

What the epoxy then filler procedure really needs is a cost/benefit analysis. I've done work both ways, and one thing I can say for sure is that epoxy then filler is a time consuming P.I.T.A. So what is gained by this procedure? Clearly the author of that test did not test the one advantage of epoxy then filler, which is corrosion resistance. Filler absorbs water and epoxy doesn't, so if the paint film is compromised, the epoxy will do a much better job of protecting the metal. In practice, though, I don't think this is much of an advantage unless the vehicle is exposed to a harsh environment and getting chipped and scratched without any maintenance, i.e. touch-up. In my experience, filler failure to to corrosion of the underlying metal happens, but is rare, so in my opinion, to go through all the extra work and expense, especially on a vehicle that won't be left in a chipped or scratched-up state, is a waste of time and money.

I said it on the ABS forum when the "test" was first posted, it means next to nothing. The epoxy/filler debate was not tested at all. What was tested was the Picklex/epoxy NOT the epoxy OR filler.

I THINK (I don't know because I have not tested it) the Picklex could have been used properly, but it wasn't in the test.

Brian

agreeing with the posts above here

while filler over primer is best if the paints gonna get beat up good, id also ahve to say in those situations, the owner of the vehical doesnt care about rust anyways

i mean if your not bothering to brushtouch your car, theres a 99% chance that you dont care if it rusts ... unless your the kind of person that will drive 200 miles in the dead of winter, on the highway, following a salt truck, letting the salt beat the snot out of your car, then expect the dealership to fix it perfect for you like its not your fault in teh first place

i see that he mntions in both cases that its the MATERIAL that failed, and NOT the bond to the metal. so either way the material stuck to the metal just fine

and honstly, if your panel is taking that much of a hit in the first place, your not gonna be crying if your previous work stuck, because you require more body work anyways ... so if the old stuff peels of your just that much closer to having the panel stripped again

i only see filler adhesion being a problem when it comes to panel flex / vibration, in something like a 1000 hp street car or an off road truck. or due to weather conditions, be it extreem heat / cold causing panel expansion & contraction, or from hail or the weight of snow

To me the great advantage of using the epoxy primer in hot rod and restoration work is that the metal is now protected from further corrosion and the rest of the work can proceed at ones leisure..Since most hot rod and resto work is long term this results in an advantage to the owner and or shop owner since one is not having to do over any rust removal. Of course one will need to sand to get the tooth for re-coat if one is past the re-coat time..

This procedure may not apply to a collision shop where the car comes in and goes right back out when done..

OMT

__________________
I would rather make it work than make it popular..And if it does not work it will not be popular..

I've done Real World tests where one side of the vehicle was done with epoxy then filler and the other side filler was applied to bare metal and have witnessed time and time again the side without epoxy failed. These were done on major corrosion repairs, cab corners, box patches, rocker panels, etc... I live in the rust/road salt capital of the world-Marquette County in Michigan's Upper Peninsula!

Now if you're working on a garaged kept show queen then maybe you feel the epoxy under filler isn't needed, but in my opinion there's no sense in doing a job half assed.

I agree with Barry,
In the test the epoxy's adhesion was definately compromised by poor prep work, or poor application, or overcooked at high heat, or it has exceeded it's shelflife. The adhesion I obtain from the epoxies I use is far better than any polyester product available period!!!!! I have never seen epoxy seperate the way the author shows when properly applied unless the product itself is old and has done bad. I feel sorry for the people that have seen this bull**** test and believe the results.

Maybe I should do a real test, or maybe Barry has some documentation already available.

Great info so far everyone, From what I've read from the post it's still better to epoxy over the bare metal then fill and re-epoxy. Now something that was said in one of the post did bring up a question. If yhou are doing say a floor piece and you going to say cover a weld line on the floor, from what I read here is even with the bumps and jumps of a truck epoxy to bare metal followed by filler and the re-epoxy should hold no problem. Sound good to me. Have a great turkey day..

Hey Barry.... Maybe it was the products that he used. He should have used SPI. LOL

Realistically, what did that test prove? Not really a thing. The products are not made to hold up under those conditions. As ws stated, if the panel is damaged that way, the stuff will need to be removed anyway. It also appears to me from reading the article that everything was rushed on this test. I also do not usually believe a test when someone is out to prove a point. A test to determine which way is better, with no opinion one way or the other is one thing. To do a test when you already have an opinion, almost always will have the result that the tester wants.

Aaron

First not enough info was given as far as a time line.

What I could pick up is first major problem was the lamp on the epoxy.
Second major problem is one coat of epoxy was applied, LF is thin and two coats for maximum strength should have been used.

Another thing is the LF is very slow to dry so 30 minutes is no where near long enough before applying filler.

Used as sealer shops will tell you anything under two hours and the it will cause die-back in paint.

He seem to have this "thing" about open coat times and from reading I think he had his thoughts back-wards as to the meaning.
Also body-filler stays kinda flexible for first day or two than gets brittle.

Before the test the panel should have sat in a corner for a week or longer and then the test performed.

If you don't know how a product works, how can you test it?

It just like painting base over epoxy.
*First two days heavy taping can pull the base of and a scraper will shave the base off.
*Third day, you might scrape chunks of base off but not in sheets as in day one or two.
*4-7 days base is starting to stick like glue.

The same above time-line happens with clear over base coat, first two days break the clear and it will peel off in sheets.

From the text of the "Epoxy or No Epoxy Under Filler by
Serge" page:


I don't really think the guy's test was all that invalid for the specific property he chose to test, an adhesion torture test. It's not too hard to believe this is what might happen in a wreck. But so what? We are not trying to hold our cars together with filler. In the case of a wreck it will need to be fixed anyway. The important thing about epoxy under filler is again, corrosion protection. I have no doubt that epoxy under filler is superior in this regard. The reason I'm saying it may not be necessary for everyone is that for many environments and vehicles, it's just overkill. Generally, the only shops that do this are high-end resto shops. Now I have not worked or lived in the Rust Belt, so I'm sure what baddbob says is perfectly valid, a rust repair down low on a vehicle exposed to salt will definitely benefit from this procedure.

What I mostly object to is that any departure from accepted dogma is met with a harsh reaction. Technicians who put filler on bare metal are not doing anything wrong, they're just not doing it "your way".

RETRACTION!

Unless I find out different I have to retract my comments about using Picklex being the cause. I hadn't read the link and no where does it say he used any metal treatment. Now, I will bet a shiney quarter that he did say that when it was originally posted in the forum. But I certainly could be wrong and be thinking of another similar test.

I do remember bringing up the same issues though such as the abusive test teaches....what?

I just wanted to make clear I do NOT KNOW if any metal treatment was used, I do not want to accuse the tester of anything. Right now, I will take it at face value and leave the test be as described.

Brian