Color Sanding and Polishing is probably the most important aspect of a killer paint job. Almost all paint jobs will leave some defects and flaws, that can be fixed with a little sanding and polishing. The flatter the paint, the better the shine. It's that simple. The process of color sanding isn't an easy one, but the rewards are well worth the work.
The tools and materials needed are as follows. Sand paper, polisher, various pads, compounds and polishes, and sanding pads. Below is a pic of the main products that I personally use. There are a ton of products on the market, so one can pick and choose what's right for them. I use what i do, because these are the products that give me the ultimate shine. The polishing aspect is where all of you hard work starts to pay off.
Color Sanding
But before we even get to that point, we need to sand the paint. Color sanding is the process of flattening the paint to allow the light to reflect on a smother surface and provide a much better shine. Color sanding is done through wet sanding with micro fine sand paper. The starting grit of the paper depends on the surface you will be sanding. Very visible orange peel will call for more aggressive paper such as 800 grit, while a factory paint job will normally call for a 1500-2000 grit paper to start with. This is a judgment call, really, but an important one. When color sanding, you are removing paint, so if you start out too aggressive, you run the risk of cutting through the paint.
Depending of what grit you start, you will then need to move up in grit in stages. This is important because you will need to remove the sand scratches of the previous grit. 1500 grit paper will not remove 800 grit sand scratches very well. Moving from 800 to 1000 to 1200 to 1500 to 2000 will provide you a much better finish to work with, and a shine that is amazing. You can go up to the 2500 grit, but I've never found it necessary. Your compounds will clean up the 2000 grit sand scratches with ease.
One this I do recommend is using a foam sanding pad. This allows you to sand the surface more evenly. These pads are pretty cheap, so grab several of them! They last a long time, and come in handy for many sanding operations. They will conform to contours easily, and make sanding a lot faster. These sanding pads also work well as squeegees to help to keep track of your progress by drying the surface.
Your first grit will be the part where you want to cut the paint as flat as possible. You'll notice right away that the paint will have a glossy and matte finish while sanding. You know when the paint is flat,when all of those glossy low spots are gone. On a factory finish, this will happen very quickly, because the orange peel is minimal. You'll want to constantly keep track of your progress by squeegeeing the the water off and viewing the surface dry. The pic below is a flat finish after the first grit is used. This is what you want to see. No glossy areas!
Now, the rest f the process is spent getting those sand scratches out with finer grit paper. The cool thing is, as you progress through the grits, you'll notice the paint starting to become more glossy. The real gloss comes when you start to compound. But before you compound, wash the car thoroughly and clean off all of the sanded paint left behind. The cleaner the car, the less likely you are to scratch the paint while compounding/polishing.
Compounding/Polishing
Here's a pic of the materials I use for the polishing process. I always start with a compound and always finish with a finishing glaze. About a week later, I will apply some Zaino Bros polish for an amazing show car finish.
The pads I use are probably the most important part. I really like foam pads, as they stay clean longer, and provide a very slick finish. I always start out with a wool pad on new paint, because it allows the compound to cut better, and seems to go farther. My second pad will be a medium cut foam pad that really starts to bring out the shine. I'll use this pad with a medium cut polish also. I'll then go to a soft polish foam pad with a micro finishing polish that gives you a shine that is amazing. I'll finish it off with a soft finishing pad and some high quality glaze. This will lock in the shine, and the reflective quality is simply breathtaking.
This is a pic of what the paint looks like after the second stage of polishing, compared to a sanded area. There's a big difference, but this is not the end result. Notice how the pearl flakes start to really stand out, when compared to the sanded area.
That's pretty much the process. It's not a complicated procedure, but it is a lot of work. It's much easier on painted surfaces that have less orange peel, like a factory finish. This is also the same process used in blending spot repairs, fixing runs and bugs and dust in the paint, and many other paint flaws. I'll touch on those next.