Thoughts about Ammonia/Salt Patinas
1. I probably don’t have to wash off the salt afterwards – the ammonia probably bonds with the chlorine ion and passivates it, especially if there is an excess of ammonia.
2. I don’t think I have washed the salt of all of the other ammonia/salt patinas – and I haven’t witnessed them pulling in moisture through the krylon to catalyze a green color. Did I wash the Custer piece? How about Pathway to Enlightenment? I don’t think I did. Pathway to Enlightenment has had a very stable patina for the past 8 years.
3. The white residue on the Custer piece is probably ammonium choride – what color is NH4Cl?
4. I am spraying an ammonia/salt solution on the copper and then covering it with crinkled/rippled 4 mil polyethylene. The areas that go blue are exposed to the ammonia vapor. The areas that stay brown are wet with ammonia but not exposed to the vapor. What is the difference here? Why don’t they both go blue? Is it something to do with the oxygen in the vapor? In other words, there is an oxygen deficiency in the areas where the ammonia-wettened plastic is touching the metal.
5. Once an area has brown color, or dark brown to black, it can be very hard to get those colors to move towards a rich blue. It’s as if they are now impervious to the ammonia. Why is that? I suppose the dark colors are an oxide of copper that is non-reactive with the ammonia.
6.What does the salt do? Why are the colors so much richer and stronger with salt added?
7. Note that where the blue color is thin and you can see the copper through the blue, the color appears to be actually green.
8. I have some blue solution with copper in ammonia & salt – I just sprayed that on my patina – maybe that will help me get more blue.
9. Heat helps the patina significantly. I get much better patinas in the summer. For the winter – try putting a heater under the patination table.
10. Concentration helps too – but where can one get concentrated NH4 these days? Maybe my brother-in-law could get me some.
11. What effect does the sodium in NaCl have on the patina? Would KCl be different? Or CaCl2 - used for melting ice.
12. The blues are very muted without the sodium chloride.
13. What effect would Copper Sulfate (Root Killer) have? Its already blue, and in crystalline form. Look it up on Google & Yahoo – maybe someone understands this.
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