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Old 04-02-2010, 08:01 PM
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Unexpected test results

Today the epoxy was cured .......To test it, I stuck my fingernail in it to see how hard it was, my nail couldn't catch hold so it was ready.
I started by putting a blob of bondo on unsanded epoxy primer and stuck two pieces of 3-M duct tape on the hood.
I pulled the tape of quickly and the primer stayed.showing some pretty good adhesion of the primer to the Ospho treated metal.
Then I got my three point putty knife placed it at the base of the blob of bondo and whacked it with a hammer...to my surprise the bondo split leaving a small amount still on the hood.
Then I tried scraping it off,some more came off but I had to sand the rest to get it all off.
After I sanded the bondo off I stopped so you could see the primer still there.
If you look close, after I sand the bondo off you can see the Ospho coating still there ,it looks like an e-coat at the edge of the shinny sanded metai theres a grayish ring just before the black primer.http://www.streetfire.net/video/osph...er_1472412.htm .
I always sand the primer before I start applying the bondo.I really thought the bondo would come clean off the primer but as you can see bondo sticks to unsanded primer extremely well.I was surprised and impressed to say the least.
I'll still sand before filling but its not really necessary.
I primed the other side of the hood after all this ,and We'll test the untreated side as well, but as far as primer having adhesion problems with Ospho ,Clearly you can see its not an issue when done properly.
I'll entertain any other thoughts on tests anyone would like done if there are any other ideas.
Next,I will be treating some seriously rusted ,pitted steel on that fury roof.

Last edited by deadbodyman; 04-02-2010 at 08:17 PM.
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