POR 15 and bondo
 

Hi
Anyone know if you can put bondo over POR 15, and if so is there any special technique.
Thanks

Yes you can. However in it's native state POR is horrible for things to adhere to. The place where you got your POR15 should have a product that they make that allows the POR to be painted over (it chemically etches so there is a mechanical adherence) and once that is applied, Bondo, Paint, or any other body filler/chemical should adhere just fine.

I learned the hard way, just figured all wrong and literaly piled all my bondo off. Just went back and gave it a good scuffing and cleaning to take a light film the por left behind and bondo stuck fine

Unfortunately you just eliminated the protection of the POR15. When you break the surface of the film you have defeated the purpose of the POR15. It is a sealer not a rust converter.

Next time, allow the POR15 to cure to a "drag tacky" state (a paint brush should have a slight "drag" when being pulled along the treated surface) and then apply the bondo. I'd suggest using the POR putty instead of bondo since the bondo will actually absorb and retain moisture.