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| Joined: | 03-12-2005 |
| Location: | Mesa, Arizona USA |
| Posts: | 338 |
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It depends on where the rust is and ease of access, how bad, and how much prep you can do. Treating rust on the outside of the fender is easier then on the inside if you don't take the fender off.
Since I live in Mesa, AZ, the environment will be different than Oregon, but the basic principles still apply. I can give you my experience with some products that I think are better. I tried POR-15 and overall found it was okay. A better product for me was Zero Rust. I also use a product called Picklex-20.
The important thing though is the prep work of the sheet metal. Normally I remove as much rust as possible. If the metal is pitted or is going to sit around for a while before I can prime it, I use the Picklex-20 to treat the metal and convert the rust. Spray it on, rub it in while it works for a minute or so and then wipe any excess with a paper towel and let dry. Parts kept in the garage will stay clean for a long period of time. Depending what has been cleaned, I either epoxy prime (exterior pieces) or use Zero Rust (chassis pieces or interior pieces).
I also used Picklex-20 for those hard to reach places, like inside the doors. After allowing it to thoroughly dry, I then used the Zero Rust to further prevent rust.
As for the anchor/base for Bondo or epoxy, two different products. First the bondo part. There are proponents of both schools. Bondo direct to metal or prime and then bondo. The important thing is to make sure the metal has enough "bite" for the bondo to hold properly. Also, it depends on what product your are using. The tech sheets will outline the proper use of their product.
Tests I have seen by a couple of guys in the field showed a slight edge to bondo direct to metal. Both methods worked. These were not scientific tests. The guys got some metal, prepped it different ways, tried a few different things and then waited. Then they attacked the metal to determine how it all held up. They did both bondo to metal and bondo to primer to the same metal.
When you say epoxy, are you referring to epoxy primer? If so, it performs the similar function of sealing the metal and offering good rust preventive measures. Again, depends on what you are trying to do. Good metal with little rust, sand, treat with Picklex, epoxy primer, sand, and paint. Metal that has heavy rust or pitting, I'll sand what I can, sandblast if needed to remove as much rust from the pits, treat with Picklex, cover with Zero Rust, and then cover with UV inhibitor coating. If metal has really bad rust or pinholes, I replace the metal with good.
Hope this helps some. I'm sure others will chime in with their experiences.
Art