The sander used with the Scotch Bright pads is an Air Powered D.A. [duel action] sander, the type used for auto body work.
http://www.harborfreight.com/6-inch-orbital-composite-sander-65173.html
It does take a decent sized compressor to run. I don't think it will work with a 2hp Home Depot compressor used for filling bike tires.
In most reads regarding gel coat restoration it's recommended to wet sand first, using wet or dry sandpaper if the surface is really bad.
The goal with each step you take is using a finer and finer grit to remove oxidation and to smooth the gel coat.
Basically, as the gel coat wears away you're left with a microscopically rough surface.
I don't think the oxidation is something that forms on the surface, but is more like the remaining bits of the existing very top layer of gel coat that's left after most of the top layer has worn off. So you're really removing damaged gel coat to get to a new smooth surface.
But, and this is a big but, you want to start with the LEAST aggressive "grit" that will do the job.
It could mean all you need is polish with a rotary buffer, Or it could mean compound and polish, or sand, compound and polish. All of these have finer and finer grit, but they are ALL abrasive.
What you want to do is find a spot that representative of your boat's surface.
Try a cleaner wax.
If that doesn't do it,
Try polish, if it didn't clean up and shine,
Try compound.
If it's still is dull and oxidized,
Try 1200 grit, wet or dry and soapy water,[or the Scotch Bright] and if it still looks bad, or, if it's way way too much work to make it look good, get even more aggressive with 600 grit.
Remember the more aggressive "grit" , polish, compound, sandpaper, whatever, you are removing gelcoat and there's only so much gelcoat there.
So you want to start with the LEAST aggressive method to determine what you need to use on the rest of the boat. Use only the amount of "grit" you need.
I started out with 1500 dry paper but found 2 problems with that right away.
1. As the gelcoat was not perfectly flat, I was sanding high spots but not the low spots.
As I was sanding away faded gelcoat on the high spots and leaving faded gelcoat in the low spots, I was getting a "mottled" look.
I think this could occur using dry, or wet or dry paper. At least using it with a pad. [Possibly you could wrap wet or dry around a sponge, and hand sand but... you're hand sanding]
2. I felt like I was removing too much material.
My goal was to remove oxidation, remove ground-in dirt and smudges and to smooth.
The Scotch Bright and Simple Green did all of these things while removing less material. They also were flexible enough to get into the low spots leaving a much more even looking finish.
I had a 6" pad but cut the Scotch Bright about 1" larger, to avoid hitting the edge of the sanding pad.
After the green Scotch Bright, which is about 600 grit, I used the gray Scotch Bright, which is about 1200 grit.
I'm sure this is way more than you wanted to know, But I didn't want someone to jump right to sanding if the boat didn't need it.
I think the real key is the rotary buffer, the duel action type that just "vibrate" really don't have the power to do the job, or it takes forever.
With the rotary buffer you are actually removing some material, but you can cut through. Be sure to keep the buffer moving.
rj
