Painting the body of a Hades

So, I think my problem is that I haven't adequately prepped the exterior surface. I had run some 200 grit over the outside to "rough it up" but neither high heat grill enamel nor plasti dip stayed on the mod for more than 3-4 days before wiping off. Suggestions? Pic is of what it looked like right after painting (aka pretty freakin' sweet)

Maybe try a bonding layer? Hit it with some primer after a rough sanding, let it dry, smooth it with 600 grit, then hit it with a coat or two of the paint smoothing with 1000 grit between coats. A protective coat of clear might not hurt it either. I know its tough to do, but after painting I'd also let it cure for about a week before use.

This is why powder coating kicks ass. Dont know where you are located but if you wanted just the tube portion coated and covered shipping I could do you a solid and give it a coating that will take abuse lol. The only downside to this all is I am up in Canada so might not be worth it to you.