When copper tarnishes, it first forms Cu2O, which is reddish and gives old pennies their appearance. This is what I wanted, and you can get it by waiting. That's how pennies get it. I don't have the patience that a penny has, so I looked for methods of producing it. I found US Patent #6261953, which gives a lot more information than needed for ageing copper leaf, but tells just what chemicals you need. Luckily, they are ammonia and hydrogen peroxide, stuff practically everyone has. You mix these two chemicals and apply them to the copper. I first experimented on a new penny, and it quickly gained the appearance of an old penny. Here are pictures of what it did to the parts of the MWM that I have thus far copper leafed.
Before chemical treatment... |
and after. |
The difference in lighting makes it a little hard to see, but the copper is aged. Not excessively, but if you compare to the pics in the last post, you see the bright copper look is definitely gone now. Unfortunately, the effect can vary with the amount of exposure of the copper to the solution, and probably with a lot of other conditions that I don't have under control. For the heat ray projector, this isn't a problem, because it's pretty small. The upper side of the hull is another matter. It's like a billboard, and the variable amounts of tarnish lend it a mottled appearance, not what I wanted at all.
I'm thinking about ways to overcome the mottled appearance. If you've got any ideas, please leave a comment. Meanwhile, the lower hull need copper leafing and ageing, and the gears and motor need to be installed and the internal wiring completed so final assembly can take place.
Next time: motorization....
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