It's a bit of a shame as I still have a lot of detailing gear, my machine polisher and loads of products to use. some of them are old hat now but they work and they produce decent results.
My Father had two stone chips on the bonnet of his 3 series that had started to rust. Obviously he wanted it sorted as quickly as possible to make sure the rust does not spread. There's also a nasty chip in the roof just above the windscreen that's going to need attention very soon but decided to have a go on these two small chips first.

I used an abrasive pencil to dry and clean up as much of the rust as I could.


I decided to treat the two spots with Krust just in case I left some behind.



I applied two coats of primer to the chips sanding with 1000 wet & dry between coats.


I applied 3 coats of paint, flatting between coats until the new paint in the chip was level with the surrounding paint.


Unfortunately this is where I made a mistake. I should have left the paint a week or so to ensure it went rock hard. Although the paint was dry it was still much softer than the surrounding paint. While machine polishing the paint in the chips cut back quicker than the surrounding paint which meant you could still see the indentations of the chips. However it's still a massive improvement over the two chips and will ensure no damage will come from the rust.

Once the paint has gone rock hard over the next week or two I'm going to have another attempt at filling the chips up with paint. This time I will give it a few weeks to go hard (1K acrylic has a habit of taking a few weeks to go off properly) and have a second attempt at flatting the paint back and polishing.
I used a heat gun to try speed up the drying times but while I was waiting for the paint to dry I got on with installing this...



