Should the copper workpiece be polished with white corundum or brown corundum?

Should the copper workpiece be polished with white corundum or brown corundum?
White corundum and brown corundum are both common abrasives on the market. The main components are alumina powder, and the content is very high. Then the copper workpiece should be polished with white corundum or brown corundum for the matte effect of oxide skin?
In fact, both white corundum and brown corundum can be used, but in most cases, brown corundum is used, because the hardness and grinding force are sufficient, and the price is cheaper than white corundum.
Although white corundum and brown corundum have high alumina content, there is still a big difference if it is shown in numbers. The alumina content of white corundum is above 99%, while the alumina content of first-grade brown corundum is only above 95%. Although the raw materials of the two are actually similar, the higher the purity, the more difficult it is to exercise, the greater the cost, and the price will naturally only go up. Although the price of white corundum is more expensive than that of brown corundum, it also has the advantage of being expensive. Because the purity of white corundum is high enough, the hardness and fire resistance of white corundum are also much better than that of brown corundum. Therefore, white corundum has always taken the high road, and many things that brown corundum cannot do are made by white corundum. Just like the same grinding process, the workpieces ground by brown corundum are not as fine and bright as white corundum; however, in terms of the deoxidized and matt effect of copper workpieces, brown corundum is still higher than white corundum in terms of cost performance. .