I take the top off a fresh bottle of ca and fill it to ¾ with acetone, that's my sealer.
Then as much ca as i fancy or can bare, the blank is already at 600 grit before any of this.
I then apply a coat of Ajax or pummis powder and finish with toothpaste or scratch away.
I have no complaints and a shiny sometimes minty finish, fine for pen chewers they get clean teeth and fresh breath.
Try it, you won't be paying through the nose for the latest must have init?