I've bought a 20yo car that is in generally good condition but for a few chips and scratches along the front (I'm guessing where rocks and gravel have been flicked up over the years). Most of them are starting to form rust. The smallest is just a few millimetres across whilst the biggest is probably 10mm.
Whats the best way to fix this? Grinding, priming, filling and respraying seem like overkill, but is that my only option?
If you want the job done right, then yes: grinding, filling, sanding, priming, and spraying are your best option. There are alternatives out there. Duplicolor makes color matched kits which allows you to paint in the smaller chips (it has an abrasive, color paint brush, then a clear coat to go over the top). I haven't used them, but the product looks like a winner. I'm not sure it's going to work for the larger chips, though. Your problem, however, may be the rust. You cannot just lay over rust with paint and expect it to last.
I found this video on YouTube. It seems fairly comprehensive as to minor chip repair. He goes over all of the basics up to the painting of the vehicle.
This guys gives a pretty good presentation on how to do all of this with rattle cans (spray cans). Two things I would not do which you see in the video is: don't do this on a windy day. You'll make a mess of things. Second, do not use a scratchbrite pad. They can cause you all kinds of issues with paint adhesion and orange peal effect. He also does not explain to you about how to do use the buffing machine very well. If you are not careful, you can cut right on through your brand new paint and you'll have to do it all over again. Use the machine lightly and be careful near the edges.
You can go to a paint store which sells automotive paints and have them make you a can of color matched spray paint for your vehicle. I don't know what the local laws are in Australia, but they'll be able to tell you at the store.
You shouldn't be afraid of doing this yourself. It can easily be done with spray cans and have a professional outcome. Two big things: be patient; be clean. Both will have a large outcome on how everything will turn out.
If the rust is severe I use a dremel to carefully remove it very locally. Then use a cocktail stick dipped in paint to fill the scratch. Build up the paint each time it dries till it is above the surface paint. Finally, t-cut it back till it bends with the surrounding paint
The quickest/cheapest fix I could find was to use a matching shade of paint and dab on the rust spots. For spots where rust has started creeping into the sheet, sand down the spot to remove all brown stuff and then dab the paint. While it does not helps with the looks, it is extremely effective till you get to the proper body job. Has worked well for me so far.
