personally I use my sewn cotton on black and green then I'll use loose cotton for my white and my blue In that order. That's for my steel and just a heads up black will take etching off ask me how I know �� U will also notice there will be build up or grease left over from the compounds I use brake fluid to remove it before using the next wheel to avoid contamination...

My woods I use Tripoli on sewn then white loose cotton, I also use different wheels for woods to metals

My horn and acrylics, kirinite polyester resin, I use black sewn then white loose cotton...

I hope that helps!
Good luck!