Polish / Compound Abrasive Abilities:
The abrasion or cutting ability of a polish on a 0-10 scale; least abrasive to most, a rating of 0 would constitute a functionally nonabrasive material (i.e. diatomaceous earth or Kaolin) a 10 rating would be 800 grit abrasive.
The most common abrasive used is silica however; many formulators are also using aluminium oxide. Most good compounds and polishes contain diminishing abrasives and are a combination of both silica and aluminium oxide. Think of them as liquid sandpaper, they are formulated with a lubricant (polymer or solvents in a water-emulsion) and an abrasive size of approx. 0.3 –0.4 micron, (diminishing abrasives) are minerals that diminishes with friction heat, buffered or cushioned in a lubricating oil film, usually in a semi-liquid paste.
Most good compounds are a combination of both silica and aluminium oxide. Some very abrasive compound polishes don’t feel abrasive to the touch because the particles are formulated in a water-in-oil emulsion and are not released without friction-heat.
As was suggested polishes vary (like all things) on the quality of the materials used (this is the largest variable) R&D and marketing costs,