Well, I did a 56 ford shift sleeve and had the same issues with the EW mirror black. I did a water inlet with the HF red and it turned out real good.
This is my first valve cover (very first valve cover....ever lol)
You can see the wavy texture and that is from the 2nd layer of powder (to fill some of those pin holes or pores, as I call them).
Can I just get any air separator, say, from Oreilly's? I could get it today and get some powder coating done today (without waiting)....
I also sprayed the air on a white sheet of paper and I get nothing coming out. I don't see any faint water lines. I hold it up in the light to see if I can see anything and it's just as clean as when I started.