copper sulphate

copper sulfate patina to low melt alloy of Bismuth/tin

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I have cast a sculpture of mine in low 281, which is an alloy of Bismuth and Tin. On one side of the sculpture, I used copper sulphate to patina. I have achieved interesting results ranging from a reddish color, rusty, to grey and black. I have not waxed it yet, or sealed it, which I believe will deepen the results. As it is in the raw state, it is a little muddy for my liking. It does not 'pop' the way a great patina does. I guess it is lacking in contrast as all the tones are very, very deep and a bit muddy.

Metal layout

How do I make a copper sulphate solution to spray on a large piece of sheet metal so I can draw out patterns without scratching the service of the metal.