Oops.... Gelcoat mistake ...
 

I have a Baja with a black stripe down its side. The black has been showing kinda grey up close, and it's been bugging me. Plus the previous owner had applied some flames so there was some ghosting once they were removed and that was bugging me. So I embarked to fix it. First I tried some M105 and it just made it a shiny and reflective dark grey. Next I tried 800 wet sand. Then down to 400. Those did nothing. So I dropped down to 220 and tried wet sanding by block with it, back and forth.I gave up at this point and worked my way back up with 400 on an orbital pneumatic sander. But dry sanded with it. I worked in a snake pattern across the entire side. I worked and worked but couldn't eliminate the 220 scratches. They were showing through. I went ahead and pushed on and stepped from 400 to 800. Then to 1500. Tested a small section with m105 to . I still can't eliminate my horizontal 220 sand marks. What can I do? I worked the 400 longer than I care to as I'm worried I was taking off to much. Guess I just need to work the 400 longer? Or maybe put some 220 on a DA?

I've wetsanded a ton of my boats, and vehicles, and never had this issue before.

I would say.. keep trying at 400 and try to work in out.... I never go below 1000.. I used the foam sanding pad that I use as my block on a very small area then hit is with 1000 again..

When you buff out with wax/polish, you can still see it??

Yep... The 220 scratches you can. I normally don't go below 600 but felt safe with 400. But even 400 wasn't doing anything. Thus the 220. Lesson learned.

The foam pad for hand sanding is a good idea. As thats what i like to use on my DA. I normally use a rubber block by hand.