Sepias, it ain't your fault!
It's safe to say that the flaking is not your fault.
I'm recalling your posts the best I can since you started researching this project, and I can't say you've made a wrong step. The only thing I can guess is that you might not have a permanent painting set-up and because of that, you probably didn't have a moisture collection system in place.
Moisture in an airline can carry contaminants (water, oil, etc.) that will guarantee that your paint will not adhere regardless of all your efforts. I sincerely hope you can find it in your SepiasSoul not to give in to the All-Mighty temptation to throw all things painted against a brick wall in your moment of frustration, you (and your Yami) deserve better!
As thorough as you were in asking advice for the process, I'm afraid those of us who advised you, failed to provide a thorough explanation of all the pitfalls of painting. I'm truly sorry for your troubles and I hope you can see it through to successful completion. I have failed many times, only to pick myself up to continue my task, learning and improving every step of the way, but only by the strength of those that surround me.
If I can be of any good help, I will gladly do so for any fellow rider.