Thank you for the accurate explanation, I am very impressed, I feel that I am learning a lot , I want thank all of you for taking the time to answer my amateur questionWhen cementing on copper metal a slab is best because as it thins out you notice it and you can stop using it by the time little bits of coper break off and mix with your Silver metal. Copper pipe, being thinner, does not last as long. The copper in with your Silver metal doesn't hurt the cell but as it builds up it has to be removed or it will co-deposit and lower the purity of your Silver from the cell. A little copper in the cell actually helps the crystal structure grow. But since most cells today run on sterling Silver there is never a shortage of copper, so why let sloppy technique increase the copper content of your cement Silver when it doesn't have to?