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Brass is the color of copper


#1

Hello all: Another beginners question. I was soldering bright yellow
brass and copper wire together. I used hard silver solder to join
them (I am switching to copper solder from IJS). I soldered them
together stuck them in a water bath and then my crock pot to pickle.
I then took a tooth brush with soap to clean. The brass turned the
same dull color as the copper, on both sides. Why??? Is there a
max temp you can solder the brass with, and if so what is it?

Thanks:
Always learning
Carol
fleamarkt@aol.com


#2

Carol, The brass probably copper plated in the pickle. Use skotch pad
or wheel to remove the oxidation or buff it off on the wheel.
Deb


#3

Hi Carol,

What was in your pickel pot? If it was the same as what you use for
soldering silver or gold, that is probably your problem. I use
Nickel Pickel in that kind of a “marriage”.

May we all still be learning!
Joyce Albers


#4

Brass is an alloy of copper and zinc. When you heat it up to
soldering temperatures some of the zinc on the surface is burnt off
leaving only copper behind. You have to remove the copper coating to
expose the brass alloy. Steve.

Steven Brixner - Jewelry Designer - San Diego CA USA
mailto:@Steven_Brixner4
http://www.brixnerdesign.com


#5

No, the pickle simply etched the zinc out of the surface of the
brass, leaving mostly copper and the subsequent color. Polish or
otherwise abrade the surface and you’ll have the brass color back.
David L. Huffman (all questions are valid, especially those directed
at “authority”)


#6

Carol, this will almost always happen when you solder brass and
pickle it. There is nothing wrong with your pickle. The remedy for the
copper-colored brass is to pickle it in a hydrogen peroxide pickle.
I’ve seen various formulas for this solution, so I don’t think the
exact proportions are all that critical. Basically, you mix about 1
tablespoon dry sparex or other pickle, about 1/2 cup drug-store
hydrogen peroxide, and water. Use hot. This solution deterioriates
quickly, so you cant keep it in a pot and reuse it like you can with
regular pickle. It works.

Rene Roberts


#7

You hit it on the head! You have a copper surface on the brass. As
the discussion on depletion gilding of sterling to fine silver pointed
out, pickle (an acid) will differentially dissolve surface metals.
Brass is a combination of copper and zinc. Zinc is readily attacked
or dissolved by the acid leaving behind the copper. The strange way
it is bonded to the brass surface has a lot to do with the oxidation
of the metals when they are heated, forming oxides which are even more
soluble in acid. Zinc is also has a lower boiling point, 900 or so C,
vs 2600 or so for copper, so if you over heat brass you will get some
zinc depletion as well.


#8

Carol, This is a common problem when soldering or annealing brass.
The brass becomes coated w/ copper-- I believe that the zinc in the
alloy is dissolved off, in effect depletion guilding the object in
copper (I’m not quite sure of this is fully accurate). At any rate,
mix up a “magic Pickle” of 50% hot pickle from your regular pickle–
preferably clean and definately not blue-- and 50% drug store hydrogen
peroxide in a cup. After normal pickling, immerse the piece in this
solution until the copper is gone. The piece will bubble so don’t
worry. You may have to buff, sc otch brite, etc., but most of the
copper should go away. You can dump this solution back into your
regular picle when you are done.

One caution: don’t leave the piece in this pickle too long. When
the copper is mostly gone remove it. Leaving it in for hours, for
instance, will etch the brass surface.

Hope this helps, Andy Cooperman


#9
        I was soldering bright yellow brass and copper wire
together, stuck them in a water bath and then my  crock pot to
pickle. I then took a tooth brush with soap to clean.  The brass
turned the same dull color as the copper, on both sides.  Why???? 
Is there a max temp you can solder the brass with, and if so what is
it? 

G’day; I suspect that the reason the brass turned copper colour was
because the pickle dissolved the zinc in the copper/zinc alloy which
is brass, to leave a film of copper. It will buff off easily enough.

64 years ago during my first job as a lab boy I had to clean the
student drying ovens in the lab which were made of copper and also
brass (makework during vacation periods). My boss told me to clean
them with Brasso, but I soon discovered that hydrochloric acid got
rid of the oxide much more easily than all that rubbing, but left the
brass copper coloured. Which easily cleaned off with the Brasso.
Luckily, nobody seemed to notice the pits in the brasswork which
began to develop. –

John Burgess; @John_Burgess2 of Mapua Nelson NZ


#10

either that or you didn’t use enough flux and it’s fire scale, the
copper came to the top. it will need alot of clean up aw


#11

Has anyone an explanation for this? I did a marriage-of-metals
piece in nickel-silver, fine silver, bronze and brass with a sterling
back. It worked out very well, but subsequently I needed to
re-solder one of the findings. (also silver). No problem. When I took
it out of the pickle, the other metals were ok, but the brass part
was all pitted. Needless to say, I was devastated (until people
started asking me how I got that interesting texture) I’ve put lots
of brass into pickle at one time or another and have never had that
result. Is there anyone who can tell me what could have caused the
pitting on the brass only?

dee


#12

Carol, when you hard-solder brass and copper, the high temperature
produces (among other things) cupric oxide (black) and cuprous oxide
(red) on both metals. This happens whether you use high or lower
temperature hard solders. The black residue comes off in the pickle,
but the red is tougher. I find bright-dip (nitric acid diluted
50:50, with care!) to work rapidly and wonderfully for removal of
cupric oxide.

As for the copper solder from IJM, let me know if it produces a
truly copper-colored join. In my experience, none of the “copper
solders” do – they end up grey. Only the hammered pre-1981 penny is
even close in color. (There was a thread on this earlier.)

I personally often solder brass with hammered pieces of brazing rod.
It has a decent color match, but can only be used on Nugold, Merlins
Gold, etc., not standard brasses (with higher zinc contents), because
the latter melt before the brazing rod squares do. It works on
copper and nickel-silver, too (although without the color match), but
its melting point is too high for silver. HTH.

Judy Bjorkman
@JLBjorkman


#13

Thanks all for the input on why the brass turned to the color of
copper. For at least one response, the pickle was fresh, matter of
fact this project was it’s christening pickle.

I took my steel brush and brushed, brushed, brushed, and walahhhhh,
brass color again. I am going to try the solution everyone suggested
so I don’t get the bristle pattern on my piece. Thanks again, I’m
heading to my table to practice, practice, practice.

Carol


#14

As the previous posters have suggested, use the fresh sparex/hydrogen
peroxide mixture to remove the plating. I add these suggestions: use
a small glass dish (needs only to be a little larger than your
piece); set this inside a larger glass bowl. Boil water and fill the
outer bowl with the hot water (like a double boiler). Put your
solution in the small dish (you can mix the dry sparex and peroxide
in the dish on the spot). The hot water will make it work much
faster, BUT the solution WILL bubble furiously and produce a very
stinky odor. I do this outside or in front of an open window, as I
find it really irritates my eyes and makes me gasp. I thought I’d
better warn you. I do a lot of mixed-metal pieces, so have to use
this solution all the time. The average little dish full will work on
about 3 pieces before exhaustion. If bubbling slows, dump the cooled
water and add fresh hot water to the outer dish. A slightly "etched"
texture appears, easy to remove when polishing. A fresh bottle of
peroxide also works much better- if it’s been open a while, it may
not work at all. I crack a new bottle every time I do a batch: then
use the rest as household disinfectant. (My dentist recommends
rinsing teeth with diluted hydrogen peroxide; also good for cleaning
skin scrapes.) Lin


#15
   I find bright-dip (nitric acid diluted 50:50, with care!) to
work rapidly and wonderfully for removal of cupric oxide.

I made a boo-boo in the above statement – it is the red CUPROUS
oxide that is removed so well by bright dip. Oppi Untracht (Jewelry
Concepts and Technology
), p. 416, says, “Copper alloys heated to
high temperatures in oxidizing conditions form a double oxide scale
film The black outer layer is cupric oxide (CuO)… The red inner
layer is cuprous oxide (Cu2O)… Cuprous oxide is tenacious and
more difficult to remove than cupric oxide… When metal is immersed
in a pickling or acid solution, these oxides are converted into a
readily soluble metallic salt…”

The use of a hydrogen peroxide pickle to remove the cuprous oxide has
the advantage of using chemicals which are less tricky to handle than
nitric acid. Its disadvantage is that the hydrogen peroxide doesn’t
last long (Bill Seeley has a nice article on this, available for 50�
from Reactive Metals Studio Inc.). Diluted nitric acid, on the
other hand, will sit for months/years (in a safe place in your work
area) and still be useable. Another advantage is that, assuming your
nitric acid is not worn out, bright dipping only takes a few seconds
to be completed.

Obviously, the use of flux deters but does not completely prevent the
formation of these oxides.

One artist I know uses this tough, red cuprous oxide as part of the
color design of her brass pins and pendants.

Judy Bjorkman
@JLBjorkman


#16

Hi Carol

I suspect that like depletion gilding of gold and of course sepletion
silvering you have leached the surface layer of zinc/zinc
oxide. In addition zinc is quite volatile, that’s why one is cautioned
before soldering galvanized iron. Sand away the upper layer to get
down to the alloy.

Before I enamel jeweller’s bronze (Cu:Zn -80:20) I try to leach out a
considerable amount of the zinc and end up with a copper-like
surface.


#17

Hi Dee,

    When I took it out of the pickle, the other metals were ok, but
the brass part was all pitted. 

I think it might be due to electrolysis, see the thread associated
with the iron nail, silver and pickle.

Your married metals could be acting like a galvanic cell. Pile discs
of copper and silver alternatively and insert pieces of blotting paper
between each pair of disc. Now add acid, vinegar or lemon juice. Add
a wire to each end. Attach them to a galvanometer (ask your local
school science teacher). A current will pass to deflect the needle.

Sailors worry about electrolysis because it can eat up the boat.
Consequently they attached “sacrificial” anodes to the boat’s hull.
These get eaten up before the other value metals do.

Aren’t physics and chemistry grand ?


#18

To all interested fellow jewelers,

By the way,these sacrificial anodes are made out of pure zinc.Another
word for this pure zinc is “spiauter”. Just something I know as a fact
for who might be interested.

Regards Pedro
Palonso@t-online.de