taiwanluthiers Posted June 22, 2012 Posted June 22, 2012 I used my foot powered ball mill, and after about an hour and a half of milling (and a very sore leg) I noticed that the brass rod media has turned purple. I was milling 2 component, mix A which is 75% potassium nitrate and 5% charcoal. Is it normal for brass to turn purple after milling?
Givat Posted June 23, 2012 Posted June 23, 2012 I'm using lead filled brass tubing media for over 6 years and never had this color.....can you post pictures of it? try to wash it and see if it happens again.
taiwanluthiers Posted June 23, 2012 Author Posted June 23, 2012 It's brass, and instead of its usual brass color it had a dark purplish color. Could brass be reacting with whatever its milling?
dagabu Posted June 23, 2012 Posted June 23, 2012 Mumbles can give you the specifics on the why it is turning colors but I can attest that you can turn brass colors by chemical interaction. I am not aware of it causing any problems with comps but it happens with my copper measuring cups as well, they are black to dark purple just from contact with the chems we use for fireworks. -dag
Mumbles Posted June 23, 2012 Posted June 23, 2012 The thing it will usually react with is sulfur, but it doesn't appear you were milling any of that. It might just be tarnishing a little, nothing really to worry about. Copper oxide and sulfide is a blue-ish black, so it is probably giving a purple hue with the red color of the metal.
Potassiumchlorate Posted June 23, 2012 Posted June 23, 2012 That was just like a shade of violet. My brass often turns blackish.
Recommended Posts