Iv been wondering what adheres to raw steel the best and how its measured. I found one paint company publish a pull off strength test of 1100 psi. And a popular epoxy company publish 7000 psi.

Do epoxy primers adhere as well as the laminating epoxy numbers I found? I cant seem to find any numbers published for well known epoxy primers and when I asked one of the best was told "of course they did pull off strength testing but go ask PPG... Like I was asking for their proprietary secret formula.

Anyone?

Just curious, why do you need the info???? Most product testing is done under ideal prep. situations, then the weathering and destructive tests begin...... And of course, it is rare that a truly independent testing firm is doing the testing. So the tests are kind of "slanted" towards a good spec. sheet on the product. When I was doing some of my own product development years ago one of my chemical suppliers volunteered the services of their "independent" lab (different company wholly owned by them) so I could develop an excellent spec. sheet (wink,wink). Not saying spec.s aren't important I just think that usage, customer feedback, reviews and your own experimentation are more important.

DarrelK wrote:Just curious, why do you need the info???? Most product testing is done under ideal prep. situations, then the weathering and destructive tests begin...... And of course, it is rare that a truly independent testing firm is doing the testing. So the tests are kind of "slanted" towards a good spec. sheet on the product. When I was doing some of my own product development years ago one of my chemical suppliers volunteered the services of their "independent" lab (different company wholly owned by them) so I could develop an excellent spec. sheet (wink,wink). Not saying spec.s aren't important I just think that usage, customer feedback, reviews and your own experimentation are more important.

Thanks and yeah I see what your saying about independent testing..

Why? Because I cant decide if I want to apply epoxy primer to raw steel first, or if I will apply my marine epoxy first. I'm using epoxy instead of polyester resin based fillers because I'm allergic and epoxy performs better across the board.
If Iv been told and believe the marine epoxy has been 'tested' to 7000 psi, why would I apply a product with less adhesion? I forgot to mention there will be some epoxy body filler hanging onto this area because the steel parts arent available.

Okay, I get it now. I guess my question would next be....how much flex will there be in the steel and will their be much change in temperature in that steel? Most laminating epoxies are quite rigid compared to an automotive epoxy (we use them to seal up plastic bumpers because of that flexibility). If the steel you are using will not flex, isn't exposed to much vibration or temperature cycling you should be okay. If not I would be concerned as those factors can easily make a laminating resin fail in that application.

what exact product are you using ?

and what exact product are you painting ?

yeah marine grade epoxy is one of the highest strength but id never in 100 years put it on a car. so what is youre doing ?


i use
amercoat

Here's a guy that does a basic adherence test.
https://www.youtube.com/watch?v=-yA8q4K-_Bo