Ferric Chloride etching

Jewelry Discussion
21

I get PNP Blue form Techniks, Inc.
http://www.techniks.com

22

How do folks cover the edges of metal pieces being etched, so that
ferric chloride doesn’t creep under the tape (or whatever) protecting
the back of the piece? I find this to be most difficult when curved
areas are involved. Even if I use a square metal piece, with the
design well inside a border, there is still an interface somewhere
between the edge of the design and the tape.

Thanks in advance!
Judy Bjorkman

23

A really cool way that I was taught by an old friend was to use
those bubble strips you find at the pet store. You use double stick
foam tape to adhere it to a plastic shoe box which two holes are used
to thread the tubes through to a fish tank motor. Cover the strips
about an inch above and use a piecs pf clear packing tape to hang it
over the bubbles. The clear tap acts as a great resist for large
areas too. This creates a great agitation that does no tneed to be
watched as long as the piece is taped from the back and suspended in
the solution just below the surface. It is now how I teach it to my
students and it works every time.

And for those looking for PnP, I get it from Reactive Metals.

Tiffany

24

Hi Judy,

How do folks cover the _edges_ of metal pieces being etched, so
that ferric chloride doesn't creep under the tape (or whatever)
protecting the back of the piece?

You can paint the edges with red nail polish. The lacquer in the
nail polish acts as a nice resist and you can see exactly where you
are applying the resist. Acetone will remove it later. Usually I
don’t worry too much about the edges, I just file them away later.

-k

M E T A L W E R X
School for Jewelry and the Metalarts
50 Guinan St.
Waltham, MA 02451
781 891 3854
www.metalwerx.com

25

I use packing tape on the backs and edges of my pieces. I also
suspend my pieces with it. I put a long enough piece of tape the
back to be able to tape it hanging from the sides of the container
I’m using and then all I have to do is lift one side of the tape to
look at how the etching is going. This also allows for agitation as
the piece swings gently in the acid. I place the container either on
the same table that I’m running my vibratory tumbler on or on a
dehumidifier. I get really quick etches that way.

Ellen Starr

26

How do folks cover the edges of metal pieces being etched, so that
ferric chloride doesn’t creep under the tape (or whatever)
protecting the back of the piece?

I use nail polish on the edge and 1/4" on to the front and back and
then run the tape from the back to cover the nail polish. I;ve also
nail polished up and over the tape to get a well-sealed edge.

Donna in VA

27 
A really cool way that I was taught by an old friend was to use
those bubble strips you find at the pet store. You use double
stick foam tape to adhere it to a plastic shoe box which two holes
are used to thread the tubes through to a fish tank motor.

All,…Duh, lets keep it simple OK?

Hang the piece by some double stick tape or masking tape from a
small block of plastic foam

Place an electric engraver (you know the cheap kind for engraving
names etc) next to (up against) the ‘tub’ or whatever contains the
etchant. The gentle vibrations do a wonderful job of keeping the
etched areas clean! Cheers from Don at The Charles Belle Studio in
SOFL where simple elegance IS fine jewelry!

28

I use clear packing tape on the back and straight edges now.

But I have been using Future floor finish also as a resist. I lifted
it from the current printmaking practices. It works great --see:

http://www.atlasbooks.com/keithhoward

and:

http://www.edinburgh-printmakers.co.uk/etchresearch.htm

It is a very durable acrylic - cheap- grocery store stuff- simple
removal. Paint it on before taping or use it as the resist. I strip
soaking in household ammonia solution in water- rinsing and repeat (
no rubbing)

Don’t laugh at this one:
http://www.swannysmodels.com/TheCompleteFuture.html

I have posted stuff on this on orchid in the last couple years.

jesse

29 
How do folks cover the _edges_ of metal pieces being etched, so
that ferric chloride doesn't creep under the tape (or whatever)
protecting the back of the piece?

I lay the piece on a piece of packing tape that extends beyond the
metal on all sides (or use overlapping pieces of tape if necessary,
and burnish the overlaps carefully), then burnish thoroughly around
the edges. Then, from the front, run a paint marker (with plenty of
ink flow) around the edge-- on the tape and the metal edge at the
same time. The theory is, if there’s a gap anywhere, the paint will
run under and fill it. When it is dry, I trim the tape close to the
paint.

This is pretty reliable. But for a real “belt and suspenders”
approach, paint the whole back, dry, then add tape.

Noel

30

HI,

No one seems to have mentioned the chemistry involved in these
etching processes but it might help to understand why you etch copper
upside down and silver right side up. When you etch either silver or
copper with an acid (Nitric Acid), the acid dissolves the metal into
a soluble nitrate solution and liberates bubbles of Nitrous and
Nitric Oxide gases. (4Ag + 6HNO_3 ’ 4AgNO_3 + NO + NO_2 + 3H_2 O).
The bubbles of gas obviously seek to rise and leave the solution and
so the metal should be right side up. If you attempt to etch with the
metal inverted, the gas will collect in the etched area and prevent
the solution touching the metal so stopping the reaction.

Etching copper with Ferric Chloride is an entirely different
reaction - nothing is dissolved but, rather, the copper is replaced
by the iron in the ferric chloride and changes the ferric chloride
into copper (ll) chloride in a 2-step redox reaction. (FeCl_3 + Cu '
FeCl_2 + CuCl and then FeCl_3 + CuCl ’ FeCl_2 + CuCl_2). In this
case, no gas is produced but the FeCl2 reduces to a sludge of iron
particles. If the metal is right side up, this sludge fills the
etched region and prevents any further reaction but, if the metal is
suspended inverted, the sludge will fall away. Any etching process
benefits from agitation either by vibration, stirring or brushing
with a feather or soft brush which will ease the removal of bubbles
or sludge from the etching surface.

Best wishes,
Ian
Ian W. Wright
Sheffield UK

31

I have received overwhelming requests for about my post
on Xerox Corps offer of free colour printers. I’m presuming its
still an ongoing programme as I still receive bi-weekly
correspondence from them regarding the product, the offer and have
been using one of theirs for over a year already. The link to the
application that Ihave is:

good luck to those of you who apply on behalf of your organisations
and thank you for the kind words about my sharing on
Orchid… that’s what the forum is supposed to foster-
camaraderie, exchange and good will centred on jewelry making and
related arts and sciences…

32

Karen,

You are probably using two different mordants (acid). Etching
in Ferric chloride eats away at exposed metal which needs to be
carried away be gravity. This is for your brass, bronze and copper.
Etching in Nitric acid, your image needs to be upward, as the
chemical reaction between the nitric and the silver causes bubbles.
Dipping a feather and wiping away the bubbles, allows you to see
the progression of the etch. Much like when you are piercing silver
and the small silver bits get into the way. You have to push them
out of >your field of vision.

You are mostly right. :sunglasses: But I am using Ferric Nitrate to etch my
silver. But it behaves as you say…and you helped me understand
why it behaves like that. Thanks.

This is a great thread, Alma. I’ve learned easier ways to suspend
the copper upside down. Would adding citric acid to my FN help it
etch faster? I have to research the Edenberg Etch.

Do people just drop their silver in the solution or do you all
suspend it too.

And I wish I could edit my posts. I noted I wrote “threw” when I
should have typed “through” in a previous post. Yikes! I know
better.

Carla

33 
No one seems to have mentioned the chemistry involved in these
etching processes but it might help to understand why you etch
copper upside down and silver right side up.

Helpful. Do you know the chemistry behind my Ferric Nitrate etching
of silver?

Thanks.
Carla

34 
How do folks cover the _edges_ of metal pieces being etched, so
that ferric chloride doesn't creep under the tape (or whatever)
protecting the back of the piece?

Judy, to cover edges, I use a paint pen. This is a marker with
enamel paint in it; you can get them in several tip sizes from a good
art supply store. I use a medium or broad tip and liberally paint the
edges. The paint will dry in a minute or so. I’ve had this method
work for very deep etches with immersion for 4 - 5 hours in an
agitated bath. The paint stays put. After etching, what doesn’t scrub
off with a scotchbrite can be removed with mineral spirits.

I’ve tried both UHU and Sharpie brands and prefer the UHU. The
Sharpies go dry prematurely, don’t flow properly, tips fall out, etc.
Maddening. Also, if covered when not in use, paint pens don’t dry out
like other markers. I’m still using pens that are a few years old.

Where I plan to trim the edges or want a clean border around my
etch, I use electrical tape to define the border, then wrap it around
the edge to the back. Electrical tape has enough flexibility that it
can stretch to conform to curves. Tape provides the best fail-proof
protection of the edges.

Hope this helps!
Rene Roberts

35 
Place an electric engraver (you know the cheap kind for engraving
names etc) next to (up against) the 'tub' or whatever contains the
etchant. The gentle vibrations do a wonderful job of keeping the
etched areas clean!

That seems to be the difference between most people’s etching
practices here and my experience with copper-clad circuit boards.
When etching a circuit board, we take pains to provide agitation,
which both prevents the collection of gunk on the surface and speeds
the etching significantly.

Al Balmer
Sun City, AZ

36

I use Duct tape on the front edges and back of my pieces. I also
stick them onto a floating piece of styrofoam with duct tape in the
back of the piece. The styrofoam floats in the ferric. I have two
small aquarium pumps in my ferric bath that keep the solution
agitated. Since I am usually doing large batches of etching at a
time, it allows me to do larger sheets or larger runs easily. I do
turn the direction of the etched panels every 15 minutes to assure
that each piece receives equal agitation. Since I prefer a deep etch,
I usually will etch at least one hour, sometimes up to 2 hours
(depending on the project).

Sandi Graves, Beadin’ Up A Storm
Stormcloud Trading Co (Beadstorm)
http://www.beadstorm.com

37 
How do folks cover the _edges_ of metal pieces being etched, so
that ferric chloride doesn't creep under the tape

I’ve done this: a great way is to cover those bits with duct tape.
it’s so thick and nice and structural that the acid can’t touch it.
At least, it works with nitric acid etching on silver. I’d suggest
testing a bit in some acid before you use it on some metal!

Robin Cassady-Cain.

38

I use a combination of processes, sometimes I use my electro etch
unit. I do the ferric chloride method a lot, I make my own ferric
chloride, because Radio Shack has discontinued their bottles of
Ferric Chloride, to sell people a kit of all the things you need to
do
PC boards.

I also use a resist and bead blast what I want etched.

Jerry

39

I just used Ferric Chloride to etch a piece of silver/copper mokume.
After an hour or two of etching, it came out etched, but with a
solid copper plating - no silver in sight. The Ferric Chloride was
brand new and nothing else was in the Pyrex dish containing the
etchant. I understand how 2 dissimilar metals will create
electrolysis between them and cause copper plating to occur (such as
introducing steel into a used, bath of pickle), but Ferric Chloride
is a chemical that is MEANT to DISSOLVE copper. How could the copper
plating exist in Ferric Chloride?

It was not a big problem to cure. I heated the mokume with a torch
to oxidized the copper, and pickled the copper oxide off. The piece
is now mostly silver in appearance, heavily etched, looks great, but
I am puzzled.

Mitch Adams

40

Hi Carla,

Do you know the chemistry behind my Ferric Nitrate etching of
silver?

There are probably a couple of reactions happening. The simple one is
that the Silver and Iron ions just change places

3Ag + Fe(NO_3 )_3 = 3AgNO_3 + Fe

which will result in a clear solution of Silver Nitrate and an Iron
sludge. However, there is also a secondary reaction in which, as the
salts are ionised, some of the nitrate ions will combine with the
Hydrogen in the water present to form Nitric Acid which will react
with the silver as mentioned in the previous email. The exact
situation will depend upon a number of factors including the
temperature of the solution, its acidity, any impurities present etc.

Best wishes,
Ian
Ian W. Wright
Sheffield UK