Twospoons
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Metal surface treatments
This thread is intended to be about decorative and/or functional chemical surface treatments for metals, preferably using OTC chemicals. Please add
your experiences.
Here's one I played with recently, to highlight some text etched into a copper plaque. Its based on the formulas I found here
Black Copper Patina
A solution of potassium sulphide applied to bare copper produces a black patina of copper sulphide. Not possessing any potassium sulphide I mixed
saturated calcium sulphide solution ("Lime Sulphur" from a garden shop) with saturated potassium sulphate solution ("Sulphate of
Potash" from a garden shop).
The quantities were very roughly equal (not good science, but then all I wanted was to blacken some copper  ). The resulting solution instantly produced a thick black non-adherent layer on clean copper. Diluting to 5% with
water worked much better, the reaction was slower (blackening over 2-3 seconds) and producing a thin matt black coat with excellent adhesion.
Polishing with fine steel wool to highlight the etching left the blackened areas shiny grey (like graphite), giving a lovely 'antique'
effect.
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cyclonite4
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One thing I tried once was plating a milo tin with copper (for fun). I used a dilute solution (very diute, but I'm not sure exactly how much) of
copper(II) sulfate to plate the tin by dipping the tin in a bucket full of the CuSO4. Within less than a minute, the tin was bright pink (salmon pink)
and the coating adhered to the metal (couldnt scratch off, but could be removed with sandpaper).
In theory, this could be done with any metals/metal ions because this involves a displacement reaction, the metal on the tin (probably an alloy of
metals, including tin [Sn]) turned into ions as the electrons transfer to the Cu2+ ion, causing elemental Copper to form out of solution (and plate
the metal). This will work if the metal is less noble (more reactive) than the metal ion.
Make sure to use dilute soultions though, otherwise the solution will eat through the metal, rather than plate it.
\"It is dangerous to be right, when your government is wrong.\" - Voltaire
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SAM4CH
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Very Soft Plating!
How can I get a very soft plating (2 mm thikness) of copper on Iron rod!?
I mean very very soft!
Sam
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