I think that brass in indeed more forgiving. I was electroplating copper before. I gave brass a try, and I made my first acceptable plate. I settled for a less than perfect polish on the brass, which of course meant there was no way that I could get a great polish on the silver-plated plate. However, I still managed to make a decent dag on the imperfect plate.
I am not convinced that electro-cleaning is necessary. Keep in mind that when people talk about electroplating in general, they are not addressing an audience of daguerreotypists. We are used to clearing a plate of all contaminants with ultrasuede, etc. In any case, my best plate so far was one that I did not electroclean. There was a place on the edge where the silver came off, thankfully only about 1/16″ on a portion of one edge. I was able to polish the plate somewhat aggressively without any further loss of silver.
I probably would be more open to electrocleaning if it were not so much of a pain in the butt. I haven’t found what I was looking for. The electrocleaning solution I use has to be heated. Then the cleaning process uses current in the same direction as the plating. As I read, this is going to cause the contaminants to be attracted to the plate. In any case, my best result to date was on a plate that was not electrocleaned so I am going to skip that step for the time being. Yet for some reason I am not comfortable suggesting that others do the same, so I guess I would remind people that there are so many subtleties to this all that what works for me may not work for you. It is possible that my plate would have been better if I electrocleaned it, and it is possible that my electroplating solution is getting contaminated for lack of chemical cleaning.
I electroplate several times what should be required according to the science. The main reason I suppose is that I have not been successful in getting a perfectly even layer of silver, so I have to plate to the point that the thinnest part is thick enough. I will post a pic of my dag at some point.