I myself do not like any copper in my browning solutions. I find the color to not be correct to my eye. My experience browning is that it takes many passes with even carding between every coat. It is easy to get distracted and over card an area. I use a ferric chloride wash but in a very dilute solution and only just towards the end of the process. For me to get a good brown usually takes 15 plus cycles. Best of luck with the copper sulfate and show some results when you get it down.

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