Tackling superficial rust

[luismgl]

Good day everyone.

I've been following this forum for quite a while and had a chance to observe quite a few talented craftsmen and over all car restoration artists, and since here I have encountered so many abled people, it seemed like the right place to ask how to tackle a problem in my car.




In the second picture it may look like there is rust under the paint, but it's only dirt, apologies for that.
Anyway, I believe it is visible I have a bit of superficial rust in my trunk frame, in the 1st picture it's actually raw metal or maybe the zinc coating. I would like to ask how to solve this as I don't have any sanding machines and would rather prefer not to buy any. From my online searching I have found I should sand the rust until I get the metal raw, coat it with zinc and later with paint. Is this accurate? what sand papper size thickness would you recommend?

I am rather ignorant in this area, as you probably have already assumed.
The car in question is an 96 audi a4 avant.

[stealthstylz]

240 grit will clean that off in minutes, then zinc prime and paint as you say. However before you do that you need to find out what has rubbed through the paint. If its not something that's fixable it might be worth putting a layer of sticky back plastic over the area to protect it.

[RobinJI]

As said, 240 will get it off pretty quickly. Stick plenty of primer on, and if there's any scratch marks showing through the primer sand it out with something finer like 400. (If you're using aerosol paints, if you're using 2 pack you'd get away with leaving it at 240.)

As a side point, when it comes to taking it right back to metal, try and sand back as small/local area back as possible while still removing all the rust. An Audi that age will be galvanized, and it'd be best not too remove any more of the coating than necessary.