I want to retain the 'rust blue' look that should be original to a gun, and avoid bluing the inside of the receiver such as bolt raceway, etc. I am not about to pay the cost of rust blueing to restore a $79 VZ-24 though.

What can I use to prevent these areas from being blued, that won't harm the activity of the bluing bath, and will come off easily afterward? Lacquer?

Thanks,
Todd

Are you rust bluing? If so there is no "bath". Lacquer or paint would work as a resist agent. Now if you are hot bluing and using a bath I cant think of anything that would hold up and not possibly affect the solution, maybe gold plating might for your VZ-24 <G>. It sounds like you are doing the rust blue thing though, you might have to go over it each time you card.

OOPs just read the title line all the way through! Don't think any non-metal coating will hold up to that boiling caustic....

Polish it after.