I know there are some different methods to color sanding other than hand sanding. 3M has a product that I believe fits on a velcro backing pad on you DA. I think it is called Trizac or something along that line. My understanding is this system is done dry. My paint store also has another brand product that is done wet. What can you tell me about experiences and the do's and don'ts? How fast do you move the DA? With the dry system, do you move to the next finer grit when the orange peal is gone? Any help would be appreciated.

color sanding with a DA? wow, how much orange peel is there?
I did mine by hand with only 2000. it went fast, and it's like a sheet of blue glass.

3M makes a Trisact II Hookit system that is not compatible with their other hookit systems. By that I mean the hook and loop system that holds the two together are not compatible. You can dry sand clear coats or uerathane color coats with the Trizact system. I start with 1500 on a DA and smooth any orange peel. Don't press on the DA too hard, let the paper do the work and don't be afraid to change the disks as they wear out quickly. Then I water sand with 2000 by hand with a sanding pad and follow with power buffing using 3M micro compound and then a final groom (swirl remover). Works well on light colors. I have a black '69 convert with rally stripes composed of House of Color gold metallic base with candy brandywine topcoat. This is then covered with PPG clearcoat. I start with wet sanding with 1500 using a Hutchinson Waterbug airsander (similar to a DA, but it feeds water continuously), then switch to 2000 grit. I then buff the car out using 3M Imperial Microfinishing compound using a 3M rounded corner foam pad (the kind where the surface of the pad has hills and valleys). Most white polishing compounds are about the equivalent of a 3000 grit. After the compounding (or polishing) I use my Hutchinson Waterbug with 4000 grit pads (Mirka Abralon from Finland) and sand the car again. The 4000 grit just dulls the finish slightly, but it takes out the micro sanding scratches left from the compound. After that, a foam polishing pad with machine glaze is all you do and you have a car with a finish that looks like water sitting on it. Sounds more complicated and time consuming than it is, but with a black or dark color car, you will get nothing but compliments.
I did a Corvette like that and it won best of show for paint, and I do this in my garage at home. I am not a professional auto painter by trade. The key is in the prep. Shine come from making the surface of the paint as smooth as possible. That begins with the body work, a couple of times around with primer-surfacer and block sanding until all the imperfections are removed and finishes as described above.
Hope this helps. Email me if you have other questions.

I have used a DA to color sand but i would rather do it by hand the DA marks are sometimes harder to get out and when doing it by hand with water you will know when trash is under the paper you will feell it and hear it. With a DA you will not .

I have used the Trizact system, sanding up to 3000 grit. It is supposed to be used dry, but I actually used a water spritzer bottle to wet it just a tad. I found that the scratches were slightly easier to remove that way. If I had it to do again, I'd have used a system that calls for wet sanding. I'm a big believer that the cleaner the surface is kept during sanding, the better the end result. Wet sanding does this, while dry sanding invariably traps some grit along the way. In either case, the DA is the way to go in terms of time saving, and also a great end result. Here's a pic of the side of my old ride after Trizact. It worked pretty darned well, and saved several hours in the process. The only down side is expense. Hang on to your wallet, because this stuff ain't cheap!

http://i22.photobucket.com/albums/b339/belairbobs/buffed.jpg

Thanks for the comments. I have not painted the car yet. Hopefully, next week bc/cc. I will be using a new SADA gun on this car, hopefully, it will lay very flat. There is another, much cheaper brand of pad I found at my paint store. I don't remember the brand but the name of it started with an "A". It is the version that is used wet. There are a couple of reasons I would rather use a DA. My last paint job was a 55 Chevy and it seemed to take for ever to get that much car flat by hand. Had my chest opened up a couple years ago and all of the hand sanding was not real comfortable. Especially, when you are trying to get it done shortly after the clear is applied. Thanks for all the comments, keep them coming.

If you use the DA, use an "interface pad" between the DA pad and the sandpaper. It is a softer foam pad that halps even out the sanding pressure and prevent burnthrough on edges.
Runs, sags, etc will need to be block sanded.
Start with 1500 (it's not a Trizac product) dry, wiping the disc occasionally with Scotchbrite to remove the dust. If you let the dust build up you will get swirly DA marks. You will need to use a few 1500 discs to get the job done. Then go to the 3000 Trizac with just a small amount of water. You should get a white sludge coming out from under the 3000 disc. The Trizac is expensive but I did an entire 67 Camaro shell with 2 discs. I used alot more
than 2 of the 1500 discs.
Keep in mind that the Trizac is designed to remove the 1500 grit DA scratches only ("scratch refinement" 3M calls it) it is not designed to level the surface or remove imperfections.
The clear used and the curing are big factors in how well the DA works. There are many times that if I miss the "window" where the clear DA's easy I will wet sand instead.