Copper / Copper sulfate

[gonelli]

There are a few questions in this.

 

I have been told that you can turn a copper statue blue by pouring sulfuric acid on it, because copper sulfate is made. And I was just thinking, would the statue be copper metal or would it be, at least coated with, copper oxide?

 

The other thing I wanted to know was, if this was done to the statue (turning it blue) can the copper sulfate be changed back to copper by just rubbing zinc onto it? Or would there be a better method to do this?

 

And, would this whole process really damage the statue in terms of shape and would it be weakened by doing this?

[YT2095]

sulphuric acid doesn`t react with copper all that well under normal conditions.

it also wouldn`t turn the statue Blue, only the Crystals of copper sulphate would be blue, and they would have to be Very thick to see it properly.

 

 

the addition of Zinc to CuSO4 will indeed form Copper metal and zinc sulphate.

[woelen]

If any copper sulfate were formed, then it would not stick to the statue for a long time. Copper sulfate is water-soluble. Any rain, or any attempt to clean the statue, would remove the copper sulfate.

 

Adding zinc to the copper sulfate does make copper, but don't expect that to stick to the statue.

[gonelli]

So serious damage will be done. Is there any other reaction that could be used to achieve a similar result, in terms of turning the statue blue?

[woelen]

Why not use blue paint?

[gonelli]

That's a good idea, any solvent could be used safely to remove it from the statue yeah?

[woelen]

There are paints (waterpaints, used for children's painting on paper), which easily can be rinsed away with water and a brush. These paints should not be confused with water-based permanent paints. The latter are considerably harder to remove. So, be sure to obtain the stuff, used by children.

[encipher]

Look into Patinas for metals.

 

IIRC, the 'mix' for blue is as follows:

 

Mix sulfurated potash and ammonium chloride in about a quart of distilled water. I believe the ratio is 3:40 by mass.

I'm no expert on this, but googling Patina formulas could help?

 

Check out this wiki article:

 

http://en.wikipedia.org/wiki/Patina