I had the same question and found this information on the Serotta forum.
[font=Verdana]Never having used these materials, it is amazing that the fine grit wet/dry feels more like you are polishing than sanding. But it definitely takes down the bumps in the [/font][font=Verdana]touchup[/font][font=Verdana] and along with the rubbing compound creates a smooth waxable surface. Knowing what I do now, I probably would not use any rougher than 1500 grit on any of these steps.
I found the rubbing compound, the fine grit wet/dry (1000, 15000, 2000), the tube of clear at my local auto parts store.
Here are the things I will watch out for next time:
1. sand chip lightly before applying any paint.
2. clean area with recommended or other solvent before applying paint.
3. mix paint as thoroughly as possible to get best match.
4. don't sand any more area than is necessary.
Use this procedure for long scratches and for large chips.
1. Use 1000 grit paper and wet-sand the scratch and the area around it. Make sure to use lots of water when sanding. This keeps scratching to a minimum.
2. Use DuPont Prepsol to clean wax off before touch-up.
3. Using microbrush and liberal amounts of paint, touch up the full-length of the scratch. As soon as the paint drys (10 minutes) do another coat. Repeat until you have done sufficient coats to have built a small mound of paint over the length of the scratch.
4. Let dry for 24 hours.
5. Now wet-sand the touched up surface with 1500 grit wet sandpaper. Sand in a front to rear motion since that's the direction the car is painted with, hence: you're going with the grain of the paint. Sand until you have eliminated the mound and any [/font][font=Verdana]touchup[/font][font=Verdana] paint outside of the scratch.
6. Clean area thoroughly and let dry.
7. Take a clean microbrush and begin to apply the clearcoat to the area. Don't be afraid to be liberal with it and don't try and keep the clearcoat within the scratch area. Apply approximately 3-4 coats, again until there is a small mound. Let it set and completely dry for 4-5 days.
8. Now, wet sand with 2000 grit wet sand paper. You will begin to see the clearcoated scratch blend into the rest of the paint - thus disappearing. (It produces a very gratifying feeling![/font]