Every frame I have ever had painted, or a customer has had painted (that I have worked on-wet/powdercoat alike) has had to be chased and faced to get the sand out of the threads and take down the painted surfaces on the edges of the headtube and BB shell. Even with proper plugs you still get some grit in the threads... its pretty inevitable unless you are going to some specialty place like Cycleart and paying a rediculous amount for a 1 color/no clear coat job.