mactuan12 - 12-1-2020 at 23:38
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.
BromicAcid - 13-1-2020 at 03:49
I did some electroplating of copper on a sign at one point and treated it with 'liver of sulfur' made by dissolving some sulfur in a potassium
hydroxide solution. Worked well, just wiped it on and washed it off giving a deep deep orange/red almost black coloration.
Armus_ - 14-1-2020 at 09:50
im not sure if it works but i have seen it happen before.
so there is a way to show the crystal structure of iron (not steel) by putting iron in a solution of copper chloride (slightly acidic) and when you
see the crystal structure then take it out, rince it off, and dip it in a hot oil solution
correct me if im wrong, im wanting to do this experiment but i never got the chance to do so