Compounding - This is used as the first step for areas with a lot of overall gray patina (corrosion), filiform corrosion or white milky cloudiness.  In most cases you will not need to sand or use scotch bright INSTEAD COMPOUND with Nuvite C.  Use a 450 RPM drill (a very slow drill - The Dewalt DW130 is good) with an adapter and backing pad and wool bonnet.  

We first polished much of the trailer without compounding.  We then started compounding on the top panels and realized how much better polish were were getting when we compounded first.  We started over and compounded almost all of the trailers with Nuvite C.  The procedure does a nice deep cleaning which gives you a better polish job AND makes your polish job last longer.

Despite what you might read on any other website DO NOT try to remove clear coat by compounding with G6:

The clearcoat is removed at different rates - uneven skin is the result
The clearcoat that is "polished" off is left in the bonnet and scratches!

The compounder really makes things go faster. It leaves a lot of swirls /scratches but it also takes out the corrosion. These swirl/scratches polish out afterwards.  See Tom's Page on how to use the compounder.

Always try the least aggressive method first. We found we could almost always compound with C and then polish out the swirls with F7.

We purchased a bonnet cleaning tool. This really helps keep the bonnets fluffed up for compounding (much better than a screwdriver). They are about $6.00. Most places that carry the pads for compounding probably have these.

This is the type of swirls/scratches left by the compounder.  These polish out in the steps with the cyclo

I wash the wool pads in the washing machine in HOT water.  I have washed them dozens of times and they have held up just fine.  It is much easier and less messy than washing them out by hand (After I am done polishing I AM tired) 

In the interest of greater domestic tranquility...
If you wash your rags and bonnets in the washing machine, do them at MEDIUM water level.  Run the next load of wash at HIGH water level (with some work clothes or some other non-critical lightly soiled load).  This will help remove the scum line left from the polishing cloths.

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An answer to an email about compounding:

I am hesitant to say that one specific method will be the "trick", but from my experience the compounding step is essential to a uniform and long lasting polish.  I do need to update the polishing info on our website, but just have not yet gotten around to it.  I think properly done compounding should eliminate the dark areas that you mention.  It is also important that you work in the shade and when it is cool if at all possible.

Until the aluminum surface is deeply compounded, it will have very small corrosion pits on the surface.  These pits will burnish over (and not actually polish out) with light polishing methods as are accomplished  by polishing with the Cyclo.  Soon, the corrosion in the pits comes back through the shiny outer surface.

Compounding is a high pressure low speed process.  Because of the high pressure needed, you cannot use a high speed buffer without overheating the work - hence the need for this tool.  As you compound, the aluminum is wiped completely clean and shiny by the wool buff.  This is critical to the method!  My basic method is to spread a VERY thin layer of compound (I prefer to start with "C") onto the buff with a butter knife.  I then lightly trigger the switch as I quickly pass the compounder lightly over the work.
(This is usually 3 short parallel passes.)  This spreads out a very thin layer of fresh new compound onto the aluminum. Then, to actually polish, I tilt the compounder so that the face of the pad has about a 10 degree angle with surface of the work.  The pad is touching only with the EDGE of the FACE and not with the MIDDLE of the face.  (Note: this is why the Porter Cable backing pad with the beveled edge is particularly good.)   I usually work an area about a foot square or so at a time.  I slowly pass the compounder over the area starting at the TOP RIGHT and make each pass from RIGHT to LEFT. This progression insures that the polishing pad is pressing DIRECTLY onto UNDISTURBED polish on each pass. (This assumes normal rotation of the drill.)  I make the next and subsequent passes about 2" down from the previous pass.

Best of luck with your polishing efforts!