Can I use a rust converter to protect cavities from existing and further corrosion?

No, a rust converter like Hydrate-80 will only convert the surface layer of corrosion. The area must be mechanically cleaned of corrosion as much as possible and then used to convert remaining corrosion in small pits, hardening into a hard surface that is primed for further paint coatings.

Within corroded cavity sections, existing corrosion and muck cannot be removed and a hard paint layer will simply trap any corrosion and dirt and the anti-corrosion properties will be exhausted before any protection can occur.

The best treatment for this is Dynax-S50. When sprayed inside already rusted cavities, Dynax-S50 will displace any water and arrest any corrosion. Dynax-S50 forms a soft, brown, wax-like film that self-heals in the event of disruption. It is also able to arrest existing corrosion and to provide long-term protection to pre-corroded and corrosion-free surfaces.