aslong as the metal is sealed and air cant get in she wont rust (is my understanding)
they use this sh** on the hulls of boats. full industrial usage. so i rekon it'll be ok for the inside of my panels where water shouldn't be getting anyway.

I think it's about $40/litre from Chemetall. It's like a milky consistancy.
I will post some pics of the stages/process if people want?

--- Updated ---

I'm using it on surface rust. to seal/convert the rust. then painting over it with epoxy enamel.
most issues with repairs is that theyre not sealed from the inside, therefor oxygen and moisture can still get to it and rust it out again from the inside. I used a spray bottle to squirt this sh** all over the repair from the inside to seal it.

--- Updated ---

Here's some info:

Blackguard is a liquid rust converter and primer that chemically converts and passivates rust on a steel surface forming a black film. The copolymer employed in this unique formulation exibits very low permeability to water vapour and oxygen therefor reesisting further corrosion.

Blackguard finds applications wherever there is a need to control the damaging effects of rust. Typical applications include; all types of road and rail vehicles, marine and shipping, building steelwork, bridge pylons, cranes and pipe work.

Features and Benefits:
* Water based - no toxic hydrocarbon solvent fumes
* Water based - non flammable
* Can be applied to damp surfaces
* Attractive black glossy finish
* Provides an excellent primer base for all good quality wet paint systems including 2pack, enamels and water based.
* Water wash up - no thinners required
* Economical - high coverage rate
* Long shelf life
* Only classified as irritant to NOHS
* Not classified as dangerous for the purpose of transport and storage

I have more info if requested.

Rufus