The standard negative grade copper meets the national standard GB/T467- 1997, in which the silver content of the main component copper is not less than 99.95%.
If the quality of copper can't meet this requirement, but it has to be delivered, it must be discounted.
The so-called discount is to subtract a certain amount from the price of standard products. Simply put, it's just not that valuable.
Water paste copper is not good enough.
On the other hand, if the quality of copper is better than the standard product, it can be improved appropriately, which means it can be sold more expensive, so it is called premium copper.
Different qualities have different discounts, so we can't generalize.