Hi everyone at Chemical Forum!
I make plastic parts, often covered in vacuum metalization process. Typically the vaporized metal is aluminum covered with transparent varnish and it produces well known chrome effect. I would like to achieve similar chrome finish but with colorful iridescent effect, like on bismuth crystals. As I know that iridescence is produced by hi refraction index difference between outside and inside layers and air. In case of bismuth it's made by bismuth oxides covering the metal.
I wonder if vacuum metalized bismuth layer cover with desired oxides. The process I'm mentioning is low temperature one and I'm not sure what was the lowest possible temperature to produce that oxides, I don't know what exactly oxide is responsible for this. The bismuth pellets I can buy are gray and unappealing, I guess they are uncovered or covered with wrong oxide.
Any help in that field will be appreciated