I did hear back from Durabak awhile back and meant to post there response. Was cleaning up email and posting it here so I don't loose the info and in case anyone else wants to know.
Hi Tom
Thanks for reaching out and good luck with the project!
So that definitely sounds like a really questionable application!
The first step would be to scuff the entire surface down with 100 grit, while you're scuffing obviously smooth down the bubbles, runs etc. and you should be able to get through to a fairly uniform finish. Don't worry if it's not all the same level of shine etc. as long as the surface is all scored evenly.
Then you would want to scrub the surface with Xylene on a t-shirt like material, this should really help even out any remaining differences between uncured, shiny, dull areas etc. once you're satisfied that the Xylene has done as much as it can, wait or the last xylene wipe down to fully evaporate and then spray or roll on a fresh coat of Durabak.
I would give it 2 coats for sure, and if you're changing color go with 3 coats. The main thing to do to avoid getting a patchy application is to keep the Durabak well mixed at all times and the can closed in between filling your paint tray or gun.
If there's anything else we can help with please feel free to reach out.
Thanks,
Support Team
Durabakcompany.com