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Copper reticulation


#1

Hello to all,

Gotta reticulation question am hoping somebody can answer. Is it
possible to reticulate copper? I know copper is involved somehow in
reticulating sterling silver, just don’t know if you get the same
results on a piece of copper itself (ie; 20 ga copper sheet). Do you
have to use a slightly different process to get the effect than is
followed for silver? I would TRY it myself if I hadn’t just run out
of O2 for my torch set up and no time to fetch more right when I
have this burning question. Pardon the pun! :-)~

Thanks for any help and/or theories on this topic. Have a good one!
Carol Carter-Wientjes


#2
Is it  possible to reticulate copper? 

As a guess I would say probably not. The idea with reticulating
silver, as I understand it, is to bring the copper component of the
alloy to the surface of the silver and dissolve it away in the
pickle, ending up with what is basically a fine silver surface.
Copper is generally not alloyed the way sterling is.

Tas
www.earthlywealth.com


#3
   As a guess I would say probably not.  The idea with
reticulating silver, as I understand it, is to bring the copper
component of the alloy to the surface of the silver and dissolve it
away in the pickle, ending up with what is basically a fine silver
surface. Copper is generally not alloyed the way sterling is. 

Well, then again, hold on. the point to removing the surface copper
content in reticulation is so the surface skin of fine silver plus
oxides (fire stain, etc, under the fine silver surface) creates a
surface layer that does not melt and become fluid when the main mass
of metal does. that surfaces skin then moves around on the
underlying molten metal during the reticulation process, being
affected by moving metal, and in particular, the random movements of
the surface as it’s dragged around when the underlying metal
crystallizes again, as well as expands and contracts during melting
and solidification. the texture created is simply because the
surface skin is not able to melt. Now, if one can create a similar
higher melting skin on the copper that will retain it’s unmelted
status, then perhaps reticulation or something akin to it, is
possible. I’d want to explore creating a good thick oxide layer. We
all know copper oxidizes very easily. So what if you heat it in an
oxidizing atmosphere, enough to build up a surfaces skin of oxide,
then continue heating till the metal under than skin melts. We all
know what melting metal with an oxidizing flame and no flux is likely
to do, ie create a rough nasty mess that doesn’t want to melt. But
if you turn that around, that is the essential nature of
reticulation, isn’t it. the question would be if you can get the
copper to flow around under the oxide layer without disrupting it or
burning though it too much, thus getting some sort of attractive
texture. It would likely be quite different from that obtained on
sterling or reticulation silver, since as a pure metal, it melts all
at once, not over a range of temps. I’d expect that what you’d get
might be more properly described as just a torch texture, rather than
reticulation in it’s classic appearance. But it might be something
attractive that you can use decoratively. Try it and see. Since
this would not require the extensive surface depletion steps of
silver reticulation, a few tests would require only a little bit of
time, and some copper you’re willing to risk descrying. In addition
to just the oxide layer, you might also explore various paint on
substances, such as yellow ocher, that might tend to hold the
surface together during the heating process.

Peter


#4

Thanks got these ideas Peter. If anyone experiments w/ this, please
write about it to the list. I would love to hear how this works,
classes are almost over here in NYC and I’ll soon be out of a studio
setting until late Sept. and little time to play w/ this neat idea.,
boo hoo :frowning:

Joel


#5

Hey Carol, Yes it is possibleto reticulate copper. When I worked in
semi-conductor manufacturing our equipment often had problems by
reticulating copper. The Cu was in a layer a couple of microns thick
and, when it was unevenly heated because of improper placement in
the machine, it reticulated badly. Application to jewelry may not be
so easy. Sterling can be reticulated by repeatedly heating it and
placing into hot pickle. The pickle depletes the copper out of the
alloy and leaves a very thin layer of pure silver on the outside.
This process has to be repeated several times to produce a decent
layer of pure silver on the outside. Pure silver has a different
melting point (slightly higher) than sterling. When heated correctly
the inner part of sterling silver will become liquified before the
outer layer of pure silver. The liquified sterling loses its
crystaline structure and thus takes up less space than it did when
solid. This reduction in size results in the surface of pure silver
wrinkling. This is only a bare understanding of reticulation of
sterling.

Theoretically, a similar situation can be reached using copper
because, frequently, the copper isn’t pure in itself. If you could
get a pure layer of copper on the outside to heat at a higher temp
than the inside it too should reticulate. That’s all theory. I
haven’t yet been able to get it to work in real life. I have gotten
close with a US penny. The outside layer of copper melts at a higher
temp than the zinc metal inside the copper coat. I fear though that
the zinc will go gasseous before the copper cladding gets hot enough
to wrinkle. I’ve accidentally ruined several coins trying it out.
But I am sure we retic’d the copper in our machines at work so I
know that it can be done. Sorry I don’t have a more definitive answer
for you.

Mike


#6

Perhaps theoretically depending upon what it is alloyed with but
practically you can reticulate red brass.


#7

Interesting theory about reticulation-type effects on copper, Peter.
If you take the same idea and apply it to brass-- we all know that
when brass is heated, it tends to copper-plate itself. A few rounds
of heating should produce a significant layer of copper (maybe,
additionally, one could pickle it in old pickle and wrap it in
binding wire for more copper on the surface). Copper melts at a
higher temp than brass, which seems as though it should yield a
reticulated surface-- that looks like copper!

–Noel


#8

Hi there, not being an expert in the trade and still taking classes,
I do not think that pure copper can be reticulated, as when you are
pickling and annealing silver, you bring the fine silver to the
surface and that is what gives you the effect of reticulation, and
with pure copper, what would you be bringing to the surface? Ok, with
that said (which I may be totally wrong :wink: My teacher did show me a
Japanese alloy last week of a combination of 30% Silver & 70% Copper
(can’t think of the name) that when it is reticulated it gives you an
almost sharkskin-like effect but does still have the copper-ish color
but maybe just a little lighter and pinker than pure copper, and the
resulting metal can be worked much more easily than reticulated
silver.

Mike in Michigan


#9
Gotta reticulation question am hoping somebody can answer. Is it
possible to reticulate copper? 

Hello Carol,

Just quoting here, not speaking from personal experience or
experiments which, as Peter has suggested, is probably the way to go.

In Tim McCreight’s “Metals Technic” there is a chapter on
reticulation by none other than Heikki Seppa. In the "Theory"
section (p.144) he says:

“… The rich texture of reticulation is not possible on pure metals
but can be achieved on many alloys.”

On the other hand Oppi says on p.337 of “Jewelry Concepts and
Technology” that all the pure metals we commonly discuss here
–copper, silver and gold-- can and have been reticulated, the latter
notably by Faberge.

In any case the Seppa chapter does offer a picture which really helps
clarify the whole reticulation process for me. It shows a metal
sandwich, “parent alloy” in the middle and fine silver on the top and
bottom. But, again as Peter suggested, let’s just take that to mean
that the outer layers melt at a higher temp than the core.

So if it was me looking to do this, and I was willing to shoot for
reticulated bronze or brass (having the possible advantage of being
harder than pure copper and therefore likely to keep it’s textured
surface longer) I’d try something along the lines of electroplating
the metal I want to reticulate with something that melts at a higher
temp, say copper itself or nickel or even silver depending on the
alloy we want reticulated. The plating probably doesn’t have to be
very substantial so any non-durable plating process would probably
suffice.

Another approach --pure speculation mind you-- might be to stick with
pure copper for the workpiece and plate it with something that melts
well above copper’s 1083C/1981F, say nickel or rhodium. Of course
we’re getting into some serious chemicals here for the plating
process but there you go.

Lastly, and FWIW, I could swear I’ve seen pictures of reticulated
copper (alloy?) somewhere. Unfortunately those examples are out there
in the ether somewhere just now and well beyond my grasp.

Cheers,
Trevor F.


#10

Peter,

Interesting idea. I will be teaching reticulation in my advanced
class this afternoon. While they are doing their depletion gilding,
I’ll have a crack at a piece of copper and the oxide idea. I am
inclined to think that it won’t work for the reasons you mention but
lets see what happens. This ought to be fun. At least it will get the
students to asking more questions.

Bill Churlik
@Bill_Churlik
www.earthspeakarts.com


#11

I haven=92t tried to reticulate copper but I have reticulated a bronze
material; it was I believe Nugold or Dix gold. The results were
rather nice. I used two torches with acetylene gas and recommend
some tinted goggles. I brought the clean alloy just before the
melting point and as the metal started to shine I quickly brought
the torches away so it started to cool right away (I also blow on
the metal sometimes). As the metal cooled it got those desired
ridges and ripples as when reticulating silver. Unfortunately if you
are even a slight bit off you will have a hole in the metal. What I
believe happens is that the outer side of the metal melts but the
more insulated middle stays solid giving a support that facilitates
the rippling effect. Because you need to bring it to such a high
temperature it only seems possible to do very small areas at a time,
but with some time and patience you can have a nice reticulated
piece to cut from. I really believe that you could do the same with
staight up copper.

Scott Thomson
@Scott_Thomson


#12

Greetings all, Peter.

Sure am having fun with all of the comments on copper reticulation!

The experiment involved 16 oz and 20 oz sheet roofing copper. (I use
a lot of this for the students to practice fold forming and other
things.) I heated the pieces to dull red. The oxide layer formed as
expected. But it tends to flake off as fast as it develops! (Save the
flake to re grind for granulation.) I did not quench or pickle
between heats as pickling would only remove the oxide I was trying to
build up. Just kept the heat on to attempt to get some build up. I
used a Little Torch, number 6 tip, soft flame. When I felt that there
was a possible layer to work with, I took the torch to the metal just
I would for a piece of sterling or Reticulation silver. Obviously we
are working at a much higher temperature than with silver; 1980F+
verses 1645F+. Tinted glasses are highly recommended. I was very
clearly able to see and maintain a surface that did not melt and an
obvious molten inner layer that responded to the torch exactly like
the silver would. I did pick up some melting on the back due to the
flux left on the pad. A much cleaner work surface is a must. I worked
on a Solderite pad. The metal moved just like the silver though not
as dramatically. I see definite enameling possibilities here. I was
not sure if we should be calling this reticulation, torch texturing,
or fusing. Since I was able to maintain a solid surface with a molten
inner core, I will call it reticulation. Like everything else we do,
there is potential here with practice.

I will be trying to copper plate brass and giving that a go shortly.
The trick will be to keep the copper from alloying into the brass at
the contact zone. Maybe if the copper develops the oxide it won’t
combine as easily. Someday I might know what I am doing! In the
meantime I will continue to follow the “what ifs”.

Yes, the students were suitably impressed, with their work and mine.
Nothing like performance art!

Bill Churlik
@Bill_Churlik
www.earthspeakarts.com


#13

Nickel silver and Nugold type brasses will give interesting surface
textures with the torch without doing anything else to the metal. I
remember that one gives a surface of regularly spaced squarish
holes. Not materials to build a whole item out of but nice for
accents.

Marilyn Smith


#14
Perhaps theoretically depending upon what it is alloyed with but
practically you can reticulate red brass. 

Reminds me of something I heard recently : In theory, there is no
difference between theory and practice. In practice, there is.

Altogether too true.
Deb


#15

Bill,

It sure sounds like you are on the right track. If you want to
discuss this with somebody who’s really done detailed experiments,
contact Paulette Myers, the metals professor at Southern Illinois
University. I suspect that you can contact her through the Art
department web site at SIU. She did her MFA thesis on reticulating
brasses, bronzes, and nickel [which doesn’t reticulate, it does
something else much weirder!]. As you have found, the oxide layer is
the key. She was able to reticulate metals like phosphor bronze that
are normally resistant to this by plating them first with copper.
She used spent pickle and a motorcycle battery to set up a little
electroplating bath and it did the job just fine. I’m sure she’d be
delighted to share a copy of her research with you and to discuss
what you’re finding. Her careful work sure saved me and Andrew Nyce
a lot of duplication when we started studying reticulation from a
metallurgical standpoint.

By the way, there are two forms of copper oxide: cupric oxide and
cuprous oxide. One is the black flaky stuff that you are frustrated
with, the other is the red-purple scale that stays on and has to be
removed with either pickle or strong physical scrubbing. I can’t
remember which one is which [John Burgess, are you in? :-)] but they
do form at different temperatures. If you have access to a kiln, I
suggest that you put your copper and brass sheets into it at about
1200 [and then do tests in 50 degree increments] and cook it for
about 8 minutes. This should give you a nice uniform layer – the
purple oxide will not flake off as readily during cooling. Another
possibility is that you could take the piece from the kiln already
hot and set it on your clean surface and start your torch work. If
it hasn’t had a chance to cool and contract, your scale layer might
stay put.

I use magnesia wool as a substrate. I like it because of its
refractory properties and because I can shape it to support three
dimensional forms. Ceramic wool, like the kind you can buy from kiln
makers and ceramic supply houses, also works but the particles are
extremely dangerous. The magnesia stuff is safer, although you
should use breathing protection and eye protection when working with
it. Call your favorite refractory supply house [check the Thomas
register] and see if you can get a sheet of the magnesia stuff.

I hope you post some images of what you’re doing on your site so we
can all have a peek!

good luck,
Anne Hollerbach


#16

Copper has two oxidation states. The Curpic Oxide ( black) can be
reduced to Cuprous Oxide ( red): (Cu2O): 2 CuO + CO --> Cu2O + CO2

Under oxidizing conditions conditions, this reaction does not
occur, but when a reducing environment is created CO), this
reaction takes place. And the cuprous oxide is red, and bright red
in ceramic glazes. This is the famous Ming red on ancient Chinese
pottery.

There are two problems:

  1. There is a 2nd reaction: Cu2O + CO --> 2 Cu + CO2 (i.e. if you do
    not watch out your nice cuprous oxide and thus your red color is
    gone)

  2. You need to be able to make a well controlled reducing
    environment.

The trick is to stop after the first reaction.

I have not worked to get the red patina but:

I have been doing batch copper annealing in a temperature
controlled electric furnace or kiln. The atmosphere is uncontrolled
( oxidizing) but I usually apply boric acid in alcohol first to
reduce oxide formation. I have also used sodium borate ( laundry
borax ) in water for the same purpose. I normally end up with
the red cuprous oxide on the surfaces. I sometimes get some
pieces with the black cupric oxide. I have not done this as a
finish patina or tried to establish all the parameters. I have
seen the patina finish on work from Mexico where the materials
will be heated in a partial ( probably) reducing atmosphere over a
charcoal hearth. The pieces I have seem to be gradually acquiring
the brown patina of the old gilding metal pennies ( 95 Cu- 5 Zn). I
have also achieved a fairly good red on Everdure silicon bronze
castings when removing ceramic shell investment residues by boiling
in a lye solution. The red does drift to the same brown with
time. I have not used any coating or wax on any of these surfaces
i just let the patina end up where it will.

I haven’t shown a process but this may help develop one.

jesse


#17

Greetings Anne.

Not knowing for sure if I was dealing with cupric or cuprous was why
I just said oxide. I am certainly confused over which develops and
when.

Thank you for the and lead. I do have kilns and plating
equipment. This experiment will continue.I would love to get this to
work on pieces big enough for vessels. We’ll see.

I am going to look at adding a button for “Experiments” to the
website. Thanks for the idea.

Bill Churlik
@Bill_Churlik
www.earthspeakarts.com