Issue is just that the original link was with HTTPS and their SSL cert is borked or invalid. Try this link with HTTP:
Removing Powder Coating Quickly and Cheaply -- Chopper Surplus
That said, acetone removes powdercoat. Benco B17 and MEK will also remove it, but especially with MEK, take proper precautions to protect your lungs. I've never used acetone to fully remove coating, but used it to face BB and clean up threads, etc.