Painting / Protecting Internal Areas

[JonnyAlpha]

Hi;

I have been rebuilding my Subframe and am about to enclose the main boxed area but before I do I want to make sure its protected.
At the mo it has been cleaned, rust converted where surface rust cannot be fully removed and sprayed in a coat of U-POL Acid Etch or U-POL Weld Through Primer (Rattle Cans).

Before I weld on the lid of this area should I cover it with any other paint? My guess is Zinc Primers such as these (I think they are Zinc Rich) are NOT waterproof?

I have some Epoxy Primer that I could paint over the top? It won't have the best adhesion becasuse of the Zinc Primer already there but it should provide a waterproof coat?? Or should I apply a Top Coat of some sort (Rattle Can)?

Here's a pic of the area in question, its the lower left and right sections that will be enclosed but still prone to water ingress:

And here are the plates:

The bottom plates have been renewed as the previous ones rusted out as this is the underside and is prone to catch and hold water.
I was also need to paint the inside of the bottom plates before I plug weld them on and was thinking of using Epoxy Primer with weld through primer on the edges where it will be plug welded? Again should I top coat the inside area.

The whole outer of the subby will be painted with Epoxy Primer and Gloss Top Coat (Cellulose)?

Thanks in advance for any replies :-)

 

[steveo3002]

id just drown in whatever cavity wax you feel is best ..id go with dintitrol but theres others avail

could do waxoil with a engine oil mix so its just thick enough to not run off ...slosh enough in so you can roll the frame around in the sun so it soaks into all the corners

 

[Rig Pig]

If you buy some closed grommets you could weld the ends shut then drill a suitable sized hole and pour or blast the wax oil in then pop the grommet in the hole to seal it up, that what I do with sills.