Easy Telling Brass wire from gold wire?

Jewelry Discussion
1

Hi All,

I’m cleaning out my studio…again…and have found some scraps of
either brass wire or gold wire.

Now that the price of gold has skyrocketed, is there an easy way to
tell the difference between the two?

Karen Christians
M E T A L W E R X
50 Guinan St.
Waltham, MA 02451
Ph. 781/891-3854 Fax 3857
http://www.metalwerx.com/
Jewelry/Metalarts School & Cooperative Studio

2

Hi Karen

I always use a fairly concentrated nitric acid solution to define
brass. In a well ventilated area or under a fume hood, dip the wire
into the solution. If it is brass you will get a bright green
effervesence and oxidation to the metal. Rinse with water to stop the
reation. With gold, there will be no reaction visible. Handle the
acid carefully…use rubber gloves etc.

Dave
Dave Mereski
The Goldworks Ltd.

3

Nitric acid turns brass green.

Terri Mccarthy

4

Hi Karen,

My solution is to soak the scrap in “Black Max.” The gold will not
turn dark black, but the brass and sterling will. Hope this helps.

Reba

5

Karen,

A drop of nitric acid will do the job. If gold, no reaction, if
copper it turns green.

Jerry in Kodiak

6

Karen,

If you pour a mild solution of nitric acid over indeterminate wires
and scrap you will immediately get a response from the brass…it
will effervesce with green bubbles!

Ron Mills, Mills Gem Co… Los Osos, Ca.

7

Karen, years ago, I bought a little bottle of silver testing
solution (JSP; #gt41) which is handy for identifying base metals. You
clean the metal first, then put a drop on it – base metal will
produce a greenish foam, silver a creamy white. I assume that gold
might give results similar to silver. The solution seems to be some
sort of nasty acid – don’t get it on anything else. Another part of
the problem is that the wire might be gold-filled, in which case
filing a groove into the center of it would be good.

Another test method might be to rub a bit of wire known to be brass
on a matte black stone, then rub a streak of the unknown wire on the
same stone. Put a little dilute nitric acid on each one and compare
the rate of disappearance of the two streaks.

But probably others will have simpler ways of doing this!

All the best,
Judy Bjorkman

8

Hi Karen;

I'm cleaning out my studio...again...and have found some scraps of
either brass wire or gold wire.

If you’ve got any nitric acid around, dilute it to around 50
percent, and a tiny drop on the brass should turn green rather
quickly. Gold shouldn’t change, although lower carats like 9K might
turn dark. If you want a non-toxic way to handle the whole batch at
once, put everything under a large plastic container with a small
dish of amonia in it. The next day, all the brass will have a pretty
blue-green patina (which would come of easily in pickle).

David L. Huffman

9

Thank you all for your answers. Since I don’t keep nitric acid in
the studio, this solution (pardon my pun) was the most practical. I
didn’t even think of getting a pre-made solution of “black on brass”
which only colors brass and no other metals.

-k

Karen Christians
M E T A L W E R X
50 Guinan St.
Waltham, MA 02451
Ph. 781/891-3854 Fax 3857
http://www.metalwerx.com/
Jewelry/Metalarts School & Cooperative Studio