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Etching sterling with ferric nitrate


#1

I have the etching process for copper down pat thanks to Ganoksin and
Gail Nelson’s article on the Edinburg Etch. Now I want to work with
some designs on sterling silver. I’m having a terrible time. I had
done extensive searching and reading on Ganoksin before starting this
project and thought I understood it.

I have cleaned the piece of sterling with a green scrubbie and Soft
Scrub (gritty cleanser that contains chlorine) and rinsed until the
water sheets off. I am extremely careful not to touch the side to be
etched – careful to the point of wearing surgical gloves and still
not touching that side. The instructions on the jar of ferric
chloride crystals I bought from a local jewelry supply say to use 1/4
lb crystals to two cups distilled water. So I weighed out four ounces
of crystals and mixed with 16 ounces of distilled water. I have the
piece face down in the ferric nitrate solution (attached to a piece
of styrofoam so it floats). I check every 30-45 mins to be sure no
bubbles are forming to inhibit the etching action. And still, after
over three hours, all I get is a slight frosting of the surface.
Hardly enough to feel with a fingernail.

I’ve tried the process three times just to be certain I hadn’t made
some mistake the first time. One time I decided to throw the silver
in my pickle pot for a while before scrubbing it (sounded good at the
time). No difference in the outcome. Help? I want to do some special
pins for a group gathering the first week in June and may just have
to resort to making them in copper and silver plating those but I’d
really like to solve this problem I’m having.

Dorothy


#2

Hi Dorothy,

Your title says, “ferric nitrate”, but in your protocol, you say
"ferric chloride crystals".

You need Ferric Nitrate to etch silver, not ferric chloride. Your
ratios are correct, but the chemistry is not.

I wrote an article on Ganoksin about this process.

http://www.ganoksin.com/borisat/nenam/photocopy_transfer_etch.htm

If you have any questions, please write.
Good luck!

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


#3

Dorothy - Are you using ferric nitrate or ferric chloride? You
mention both in your post. My first guess would be that you are
using the ferric chloride, which won’t etch silver.

I don’t really measure out my solution to water - I’ve been able to
base it on the color to let me know the solution is right - I get it
to a dirty orange color and it’s always worked fine for me.

As far as preparing the silver, I use the brown or green scrub pads
from the hardware store and I use a metal degreaser - it’s sold by
Industrial Metal Supply Co. I found that the metal degreaser
completely cleans the metal of any oil, grease, etc. - and it’s
fast. A couple brushes in different directions with the scrub pad and
metal degreaser, rinse, dry off on a paper towel and it’s ready to
etch. I used to use dish soap, but found it sometimes difficult to
get rid of the soap - even though it appears to be gone.

The results I’m getting now with the metal degreaser are much better
than when I was cleaning the metal with dishsoap.

Another problem could be in the resist you are using. What are you
using as the resist?


#4

Hi Dorothy,

In your description of your process you write, “The instructions on
the jar of <> crystals I bought from a local
jewelry supply say to use 1/4 lb crystals to two cups distilled
water.” Was that a slip of the fingers, or were you really using
ferric chloride? If so, then the chloride ions would react with the
silver to form a precipitate of water-insoluble silver chloride. Any
copper on the surface would be leached away.

If it was a slip of the fingers, and you did use ferric nitrate,
then I would be as puzzled as you are and ask for help too.

David


#5

Try putting it in the acid with the face to be etched UP, resting on
the bottom of the container. When etching copper, there is a residue
that falls off. With silver, that’s not needed. You may be getting
tiny bubbles and not realizing it.

Also, try a stronger mix, and see if that works.

And, noting what may or may not be a typo in your question, be sure
you have a jar of ferric nitrate, not ferric chloride. the cloride
will not work at all.

Also, though ferric nitrate is known for producing a smoother more
even etch than nitric acid itself, the etch produced by the acid is
not that bad for many uses. If you’re doing photo etching and need
that sort of precision, perhaps it’s not so good. But for many uses,
the slightly more uneven line is not a problem. a ten percent
solution of nitric acid etches silver quickly, and is dilute enough
so that it’s not all that nasty to handle, though it is still, of
course, an acid (so is the ferric nitrate solution, for all
practical purposes).

If still no joy, hook your silver sheet up to the anodic terminal of
a battery or electroplating power supply. Somewhere around 2- 3
volts should do fine. Hook the other end to a carbon rod, or gold
or platinum (or anyting else conductive that is not etched by nitric
acid). Electroetching is surprisingly fast and efficient, even with
otherwise weak electrolytes/etchants.

Hope that helps.
Peter Rowe


#6

You people are the greatest. I’ll answer everyone’s questions all in
one spot to save my typing and your reading time.

First, my face is red. Yes, I’m using ferric nitrate on the silver.

Karen:
Your article
http://www.ganoksin.com/borisat/nenam/photocopy_transfer_etch.htm

is what I had printed out for my instructions. Thank you! One thing
I’ve noticed just today is that your ratio is “Ferric Nitrate is
mixed with 1-part Ferric Nitrate crystals and 2 parts distilled
water.” I hadn’t paid that much attention to that because the jar of
ferric nitrate I bought had instructions to mix “1/4 lb with 2 cups
distilled water” so I used 4 ounces crystals to 16 ounces water.
Those directions give a 1:4 ratio rather than the 1:2 you suggest.
Think I’ll mix up a batch of 1:2 and try again tomorrow.

Catherine:
Thanks for the tip on the metal degreaser. Sounds like a good thing
to have on hand. For resist, I’m using adhesive vinyl press on
letters and Presto brand rub on design elements.

David:
Yep, slip of the fingers! My computer needs a brain checker rather
than a spell checker LOL

Peter:
Thanks for the tip on having the piece face up in the solution. That
would certainly be easier than the pontoons. Using the press on
vinyl and rub on transfer for the design, I didn’t know how they
would react with the the nitric acid so had decided against that for
this job. As for the bubbles, I know about them from working with
copper and the ferric chloride. Karen’s article has a nifty idea of
using an aquarium bubble stone which is what I used for that
process. I looked carefully for bubbles on the silver when I checked
it. The electroetching is definitely something I’m going to try
later since I already have the electroplating power supply. But I
want to conquer this process first.

Again, thanks for everyone’s time and suggestions.
Dorothy


#7
Now I want to work with some designs on sterling silver. I'm
having a terrible time.

Troubleshooting:

  1. Make sure you have ferric nitrate and not ferric chloride. Test
    with a piece of copper-based metal and see if it etches it.

  2. Use a Baume’ hydrometer (available through a photo supplier and
    some hardware stores) and check the strength of the mordant. Should
    run between 15-30 degrees for most applications, depending on
    whether you need a slow or fast etch.

  3. Switch your cleanser. Chlorine and other things can interfere
    with the mordant. Use Bon-Ami, Ajax plain dish soap (not
    antibacterial), or No Name Patina Prep. No breaking water across the
    surface allowed.

  4. Wipe down your piece with alcohol before etching to remove
    surface oil. Make sure there is no oil floating on the mordant.

  5. Mordant should be room temperature and absolutely no more than
    125 degrees Farenheit.

  6. Mix with distilled water only. Chlorine combines with many
    mordants and changes them significantly, as well as other minerals
    present in tap water doing the same.

Frankly, it sounds suspiciously like you have ferric chloride rather
than ferric nitrate, regardless of what the container says.

Katherine Palochak


#8

http://www.ganoksin.com/borisat/nenam/photocopy_transfer_etch.htm

Great article, thanks Karen.

I am going to try etching for a personal project: making 2 sterling
silver medallions for my husband and his best friend who turn 50 this
summer.

I have some process questions related to the fabrication -

I want to etch the lettering “Order of the Exploding Arrow” on one
side and the motto “Faster, Higher, Louder” (in latin of course) on
the other side (long story but short version is they have been best
friends since they were 8 years old and they still act, well, 8, when
it comes to things that go boom or exceed legal speed limits).

I assume I have to etch the back and front mottos on separate sheets
and solder them together because I can’t etch both sides of one sheet
at once?

And I want to solder on castings of an exploding arrow on one side
and a gun on the other - What does soldering do to the etched metal -
I assume it’s the same as any texturing, right?

I fear I have got myself one of those “why have I chosen such a
complex first project for etching” situations, but there it is. So be
it!

Thanks for any tips you can give!!

Roseann


#9
If still no joy, hook your silver sheet up to the anodic terminal
of a battery or electroplating power supply. Somewhere around 2- 3
volts should do fine. Hook the other end to a carbon rod, or gold
or platinum (or anyting else conductive that is not etched by
nitric acid). Electroetching is surprisingly fast and efficient,
even with otherwise weak electrolytes/etchants.

Hi, Peter,

Where can I get more info mon this method? Will this arrangement
speed up copper etching in ferric chloride? Nitric is fast enough
(for silver, of course) already, though a boost would be nice with
ferric nitrate.

I can try this with my titanium anodizer. Do you happen to know
whether niobium is OK in the acid? I’d hate to eat up my little
clip. Guess I can test with a scrap.

–Noel


#10
   Where can I get more info mon this method? Will this
arrangement speed up copper etching in ferric chloride? Nitric is
fast enough (for silver, of course) already, though a boost would
be nice with ferric nitrate.

Noel,

electroetching is fairly well described in Oppi Untracts book. But
it’s not complex. A plain low voltage battery is all you really
need, the larger size lantern battery type, so you’ll get decent
amperage.

Not sure if you titanium anozier will work. electroetching needs low
voltages, (1.5 to 3 volts, or somewhere in there), but it can draw
substantial amperages. Some titamiun anodizers can’t supply much
amperage, and many can’t be adjusted to that low a voltage. Normal
run of the mill electroplating power supplies, however, such as one
might use for gold or rhodium plating, will work fine. The
arrangement is simply reversing the terminals (anode and cathode) so
that your piece to be etched is the Anode.

You may have trouble with titanium or niobium clips. they are, after
all, covered in an insulating oxide layer, so contact with the
workpiece, especially at these voltages which are much lower than
those normally used with those clips, is likely to not give you
electrical contact. Just hang the work from a piece of gold or
platinum wire. Try the clips if you like, but I doubt they will work
well. But they won’t dissolve in the acid, so it’s safe enough to
try.

Peter


#11

Niobium should be fine in the acid. Be careful with your anodizer.
It is not really meant for this process. The current density will be
higher from a battery charger and more in line with what you are
doing.

Bill

Reactive Metals Studio, Inc.
PO Box 890 * Clarkdale, AZ 86324
Ph-928/634-3434 * Ph-800/876-3434 * Fax-928/634-6734
E-mail- @Michele_Deborah_Bill
Catalog- www.reactivemetals.com


#12
    I can try this with my titanium anodizer. Do you happen to
know whether niobium is OK in the acid? I'd hate to eat up my
little clip. Guess I can test with a scrap. 

Electroetching is covered to a limited degree in chapter 8 of
Jewelry Concepts and Technology by Oppi Untracht. Your Titanium
anodizer is too high a voltage for this purpose you need between
2-12 volts depending on metal type and electrolyte solution.

Jim Binnion

James Binnion Metal Arts
Phone (360) 756-6550
Toll Free (877) 408 7287
Fax (360) 756-2160


@James_Binnion
Member of the Better Business Bureau


#13

Hi, Roseann,

It wasn’t me you asked, but…

On silver, you can etch both sides of your metal at once, no
problem. I use an iron-on process with photocopies, and if I want to
do two-sided, I put both images against the prepared metal, iron on
one side, then flip and finish up the other side, let cool, and
remove both sheets of acetate (that the images were photocopied on).
Even easier if you are doing it free-hand with paint marker or the
traditional way, scratching through asphaltum.

It’s not a bad idea to prop your piece on edge in the mordant, if
you can figure a way. No worries about bubbles, and both sides etch
equally.

Of course, there’s really no problem with etching one side at a
time, either. Just make sure you coat the finished side well to
protect it while you do the second.

One thing I’ve discovered about etching silver-- your resist will
stick a lot better if you etch your whole sheet for one minute
before you apply your resist, whatever it is. Rinse and dry
thoroughly after etching, of course.

Also, believe it or not, the black oxide you get from using a
product like Black Max acts as a decent resist! I wouldn’t depend on
it alone, but if you oxidize your piece on the back, say, then add
tape or asphaltum, it’s kind of belt-and-suspenders…

One last hint-- When I can, I like to leave a little extra metal
around my piece to trim off after etching, just to be sure I don’t
ruin my edges if acid leaks.

Oh-- and, yes, you can solder normally on etched material.

–Noel


#14

Hi Roseann,

    I assume I have to etch the back and front mottos on separate
sheets and solder them together because I can't etch both sides of
one sheet at once? 

True, but you can cover one side with duct tape and then etch the
other side. This way you won’t run into a problem when you have to
solder your arrow.

        And I want to solder on castings of an exploding arrow on
one side and a gun on the other - What does soldering do to the
etched metal - I assume it's the same as any texturing, right? 

You are correct. If you plan ahead in your design, mark the place
where you want to solder. Mark that part with the resist so that spot
is not textured. You can also “paint” the surrounding area with
either yellow ochre or White Out. Make sure you have good
ventilation.

    I fear I have got myself one of those "why have I chosen such
a complex first project for etching" situations, but there it is.
So be it! 

I think it is great! You won’t learn unless you try, and you learn
more from your failures than your successes. Just make sure you write
everything down in your sketchbook.

Good luck!
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


#15
   I assume I have to etch the back and front mottos on separate
sheets and solder them together because I can't etch both sides of
one sheet at once? 

Two different approaches for etching with one sheet front and back:

  1. Attach copper wire to one end, preferably one end that can be
    scrapped, and suspend in the solution to etch both sides at once.
    Usually the tape tends to lose its hold in a wet environment, but if
    you want to use solder, a nonreactive solder can be used (like gold
    solder). Expediency over cost.

  2. Etch one side first, having the other side completely blocked
    with resist. Remove all resists, reapply PnP to the unetched side and
    block out the previously etched side. I find nail polish to be
    excellent for getting down into all the little recesses and
    effective.

And for those who reuse their solution, you don’t have to throw it
away. Let the sludge settle to the bottom of the container,
carefully decant the liquid and put the sludge through a coffee
filter suspended over a glass beaker or jar. After the rest of the
liquid has filtered, you can add it to the other liquid previously
poured off. The sludge can be dried and disposed of according to
your local landfill requirements. The liquid can be adjusted up or
down, by the addition of fresh crystals or distilled water,
according to the strength you need. I’ve used my same solution since
about 1997, even through all my multiple projects, plus many etching
workshops. I estimate probably 500 people and roughly 4,000 pieces,
including bracelets and collars.

Katherine Palochak


#16

Dorothy and others!

Please don’t assume that because I use an aquarium pump, that I am
using the airstone. I am not! This protocol etches best with
AGITATION. The pump is duct taped outside of the plastic container. I
use this pump because it is cheap and because it doesn’t mind being
on for hours. The vibration in the pump vibrates the liquid just
enough to keep the etched metal vibrating out of the open area. In
commercial practices, spray etchers are used and it is this constant
action that creates the etch. My process is just slower, but just as
accurate. The perk of this process, is that you can set it up and
walk away and do other things. The pontoons are work nicely for this
process, with the added perk of having a little handle to pick the
work out and see how the etch is going.

I have to go back and look at Peter Rowe’s and figure out why the
etch would work with the image side up. Doesn’t seem right to me.

Good luck!
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


#17

[be advised, it’s a long one]

FWIW, I just did a whole lot of etching in silver with ferric nitrate

  • it was a learning experience, but a pretty successful one. I used
    pretty much the method described in Karen Christians’ article; the
    2:1 ratio of water to ferric nitrate crystals worked out very well.
    (The ratio was mixed by weight, not volume, using filtered water.) I
    experimented with a more dilute solution, unscientifically reduced to
    the color of weak redbush tea, but found it too pokey and went back
    to the strong stuff. I did all the etching in a largish, rectangular
    Pyrex dish, about 8" x 10" x 2 1/2", and suspended the pieces,
    several at a time, on a chunk of styrofoam.

I started out using air stones and an aquarium bubbler, but I
removed it after only an hour or two because it was causing large
bubbles to form on the underside of the pieces being etched. (Maybe
the container was too shallow?) Placing the air pump (with nothing
connected to it) against the side of the pan seemed to speed etching
just a teeny bit, presumably because of the vibrations generated,
but I got tired of the noise and stopped using it. Maybe it took a
little longer, but sanity was allegedly preserved!

The etching was checked for progress every 30 min. at first, and
then every hour when I realized how slowly it progressed. The
unprotected areas of silver developed a dark grey or black coating,
which could be rinsed off under a steady stream of water. Gentle
brushing with a synthetic Testor paintbrush removed all of the scum
without damaging the resist.

PNP Blue was used as the resist, as the designs featured many rather
fine lines. (I was doing pseudo-champleve with Durenamel on the
final product.) The resist worked well, but began to degrade after
3-4 hours in the etchant. Burnishing it well with the iron during
the transfer process seemed to make it a little more durable - I
found it unnecessary to use a sheet of paper during the transfer
process, as the instruction sheet suggested. Fortunately, the PNP
stayed on long enough to etch the design in quite clearly, about 0.1
to 0.2 mm deep.

To replace the PNP resist when it began to peel off, I tried two
methods: handpainting with oil enamel, and applying nail polish with
a printing brayer in the same manner used for inking linoleum blocks.
Handpainting was a tedious process, and the oil enamel degraded after
about three more hours in the etchant. However, rolling nail polish
over the raised design worked well for detailed designs and could be
done quite quickly. Several coats were usually required to ensure
that all raised areas were protected, and the polish was allowed to
dry between coats. On designs with large, open areas, the polish
often went where it wasn’t wanted, but it could be scraped off after
it had dried. I sometimes had to re-scrape areas after an hour in
the etchant to make sure that no polish residue was causing problems.
The nail polish was by far the best “paintable” resist, and lasted
about 6 - 7 hours before beginning to degrade. (The backs of the
pieces were covered with plastic shipping tape, which worked just
fine.)

The final etch, which had to be at least 0.015" deep for the
Durenamel, took about 8 - 10 hours to reach; I did some pieces over
the course of two days, and didn’t notice any ill effect from
interrupting the process. Some fine lines did get broken when I
placed pieces that were already deeply etched in fresh solution, so
it might be a good idea to check pieces more frequently when the
solution is new. Baking soda was used to clean pieces when the
etching process was complete, and left a nice sheen on the metal.

I hope these notes will be helpful to anyone wanting to try this
technique - it really wasn’t difficult or even that expensive, and
yielded some very nice results.

Cheers,

Jessee Smith
www.silverspotstudio.com
near Lecanto, FL, where the air is full of dragonflies!


#18

Hi Roseanne,

One trick I haven’t seen mentioned is to use a small block of
expanded polystyrene - the white stuff - to hang the piece you want
to etch in the liquid. The polystyrene will float and you can hang
the piece by a wire so that it doesn’t touch either the sides or the
bottom of the tank. When I need a fairly large tank I just line a
cardboard box with a polythene bag.

Best Wishes
Ian
Ian W. Wright
Sheffield UK


#19
I assume I have to etch the back and front mottos on separate
sheets and solder them together because I can't etch both sides of
one sheet at once? And I want to solder on castings of an exploding
arrow on one side and a gun on the other - What does soldering do
to the etched metal - I assume it's the same as any texturing,
right? 

Roseann, can’t you mask the first side after you have etched it,
then etch the reverse? Even if you are using a film instead of the
traditional paint-on ground, it seems to me that you could leave a mm
or two unetched around the edge so that it would seal well.

Solder tends to creep along the engraved lines that I sometimes use,
so I think it would do so on etched work, too. Be sure to mask with
white-out or yellow ochre to avoid solder creeping into your etched
designs.

You know,as an alternative way to make this project, engraving is
not all that difficult, if you are not attempting to do fancy
lettering. That takes time to learn, I have heard! But I enjoy doing
engraved details on my work, and as long as I keep it , shall we say,
less formal in design, I get pleasing results. There’s no pollution
involved, and all you need are a graver & handle, a grinder,
sandpaper & a small sheet of glass to polish it on, and a way to hold
the work. A simple pitch bowl works fine. Practice on copper and on
silver sheet scrap before tackling your jewelry design, of course. I
know you like to be ecological, so doesn’t engraving make sense?

And it’s fun!

M’lou Brubaker, Jeweler
Goodland, MN
www.craftswomen.com


#20

Thanks, Jessee, for the detailed description of your etching
experiment. I gotta say, it isn’t clear to me why it might be better
to go through all that than to etch with nitric acid in 10-15
minutes. Is there an advantage to the ferric, in your opinion?

Also, did it still etch OK through the residue you described, or did
you have to keep cleaning that off?

Did you try my suggestion of etching the whole plate briefly before
applying the resist? I find this very helpful to make the resist
hang on longer, in nitric.

I use a used magnetic stirrer (bought cheap on eBay) with copper and
ferric chloride; it speeds the etch considerably, though on large
pieces, you may see uneven depth from the “currents” of the spinning
liquid. Thought you might like to know.

–Noel