Cartec is a Dutch manufacturer whose compounds are used in body shops, and the numbered system tells you where each product sits. Diamond Cut 3000 is the extreme cutting compound for refinish work, Compound 5000 is the fast cutting compound, Rapid Cut 4000 sits alongside it, Final Cut 9000 is the one-step, and Ultra Finish 12000 is the high-gloss finishing polish. Matching Unipad and colour-coded pads are available for each stage.

Final Cut 9000 for most cars, because a one-step compound corrects light to moderate defects and finishes down in a single stage, which is what typical daily-driver paint needs. Step up to Compound 5000 when defects are not clearing, and reserve Diamond Cut 3000 for refinish work such as removing sanding marks after paint repair. Always test a small section first and work with the least aggressive product that does the job.

Not strictly, but the pairing is deliberate: the green pad is specified with Diamond Cut 3000 and the yellow with Compound 5000, so using the matched pad gets you the behaviour the compound was developed around. Any quality pad of the right grade will work. What matters more is that you do not put a heavy compound on a finishing pad, or a finishing polish on a cutting pad, since either wastes the product.

Yes, though they were developed for professional use and some were designed with rotary work in mind, so on a dual action you will need a firmer pad and more patience to get the same cut. Spread at low speed, work at speed four to five in small sections with slow overlapping passes, and keep the pad flat. On soft paint a DA with the one-step compound is often the ideal combination.