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Chemical etching of copper


#1

Hello again folks. I’ve been etching copper using a ferric chloride
solution. I got the stuff in a kit that was designed for etching
custom printed circuit boards. With practice, I am finally starting
to have some successes but I’m also noticing some problems that seem
to be fairly common. I think these may be related to the different
resists I’ve tried. Let me explain what I’m doing and what I think
is going wrong and I’d really like to hear from others with an
assessment of my notions.

I’ll start with resists. The kit suggested using a permanent felt
tip marker ( I used a Sharpie). It seems that the ink does act as a
resist but I’ve noticed that it is very difficult to get a good even
coat with the ink. Variations in the ink coating result in
"etch-through" giving me smudged looking results. To get the depth I
want requires etches of 2-3 hours. I decided to try a laquer (
common fingernail polish, somewhat thinned). This gives very good
protection but presents problems of it’s own. When I have to scratch
a design through it, the final etch shows that there may have been
some lifting of the laquer around the scratches. The mordant appears
to be seeping under the resist around those lines giving an uneven
etch and fuzzy line margins. I want clean, clear lines.

My assessment of the laquer is that it needs a better bite on the
surface to prevent lifting. Perhaps I’m putting too fine a polish on
it prior to resist application? Another consideration I’ve had is
that perhaps the laquer is forming too hard of a coat causing it to
lift like a sheet when I scratch through it. The ink resist seems
too inconsistent. I’ve tried multiple coats but the solvent in the
pen dissolves the previous layer causing smearing that eventually
shows through on the etch. The ink doesn’t seem too well suited to
long etch times either. Would it help to go with a resist that has
more “tack” to it? Maybe something like beeswax or a thinned rosin
or tar? Any ideas would be appreciated.

A final question concerns the mordant. Are there other concoctions
that might work better? I’ve looked into buying some nitric acid and
constantly run into people who want to know if I’m trying to build a
bomb. Lunatics. I just want to play with metal.

Mike


#2

If you really want good results with etching, I would suggest
getting a resist called ImagOn. I ordered it from Daniel Smith, an
art firm in Seattle WA. The process takes a while but the results are
the best I have ever used. Check the process first because it must be
precise. I use box with a black light for exposure but you can use
sunlight if you make tests. Go to: www.danielsmith.com or right to
the catalog page for ImagOn:
http://www.danielsmith.net/cgi-bin/sgsh0113.exe

Ferric Chloride is the best for etching copper.

Louise


#3

If you are not etching your copper upside down, give it a try. In an
Arrowmont workshop (sorry, can’t remember which one) we taped
masking tape to the back side and laid the piece on fiber scrubbies
(supermarket) in Pyrex dishes. The sludge that forms can than fall
out. This results in a cleaner etch.

You could also try using the traditional asphaltum type resist.

Marilyn Smith


#4

Some things which might affect the results of your etch with ferric
chloride aRe:

  1. Resist–try using PnP for getting fine lines and detail. It has a
    polymer coating of some sort that binds with the carbon-rich resist
    to make a really tough coating.

  2. Make sure you’re using a carbon-rich product. India ink,
    lampblack, carbon toner from laser printers or photocopiers.

  3. Properly prep your metal. Cleanliness is imperative. Water must
    sheet off, no lint or dust.

  4. Contaminants in the ferric chloride or water can affect the
    results. If you need to cut the mordant strength, use distilled water
    to prevent hard water problems such as calcium and soft water
    problems such as salts.

  5. Brush the smut away frequently, like every 15 min. Suspend the
    work upside down to aid in removing smut.

  6. With some resists, a slight tooth to the metal can aid in
    retention of the resist. Use a high grade sandpaper in 400 grit and
    stroke in one direction. Do not sand in a crosshatch or circular
    pattern. This allows small crossover points that etch more deeply and
    cause the resist to lift.

  7. Nitric acid should only be handled by those who have adequate
    training. It requires stringent handling and disposal treatments.

  8. Adjust the strength of the mordant according to the type of
    artwork you use. Fine lines require a fast etch with a quick bite,
    open artwork requires a slower etch to prevent swirl patterns and other
    disturbances.


#5

Hi, Mike, Actually, I’ll have more complete in the next
couple of months, as I’m doing a set of tests on etching that will
be published in June. (I’ll post the article here once it has
appeared.) But I can tell you a few things. Sharpie pen is definately
not adequate. Paint markers work much better (art or hobby stores).
Their tips make really fine lines difficult, but they work well,
especially for copper, as opposed to silver. You will improve the
"grip" of your resist if you etch your plain sheet briefly and then
rinse and dry, before you add any resist. “Briefly” means 1-2 minutes
for silver in nitric, maybe 5-10 for copper in ferric. By the way,
nitric doesn’t really work on copper-- it is for silver. I have a
pen that works really well on copper. It was given to me, so I don’t
know where it came from, but it says “Decon” on it, plus some other
stuff that is pretty worn off-- maybe DAI 033 PC and some illegible
other stuff. The piece of paper wrapped around it describes it as an
acid resist marker pen. Sorry if that isn’t of any use. The
traditional material to use is asphaltum. Basically tar, obviously.
It takes hours to dry, and is best suited for covering a whole piece
and scratching through as in doing a printing plate. A related
material referred to as etching ground (it has another name, but I
can’t think of it) is also tarry, bought in little bottles in art
stores, but dries quickly. The trick is that if you dry it too
thoroughly, it chips when you scratch it. Ruins brushes very fast,
too. My own preference is generally for transfer etching as with PnP
blue or (what I use) ironing on photocopies. I really can’t type a
tutorial on that here right now, but it will be in my article. I am
testing three different methods. A last word on mordants-- adding
citric acid is supposed to help: search the archives under
"Edinburgh (sp?) etch". Also will be… you know, in the article.
Can you really make a bomb out of nitric acid? HTH!

–No=EBl


#6

Hi Mike-You don’t happen to be the Mike Honeycutt from Prescott, AZ
do you? Anyhow, I do alot of copper etching and use PCB etch from
Radio Shack. It is ferric chloride for etching computer boards and
costs around $4 a bottle. For a resist I use paint pens which you
can buy at craft stores like Michaels or Ben Franklin. They are
enamel based, not water based, and fairly thick in application.
First scuff your metal with sandpaper-I use 220, it keeps the paint
from lifting when in the etch and if your resist is lifting I suspect
it is because you are polishing the metal first and the paint does
not have a surface to “key” into. Draw/paint with the pen (there are
different tips, thin for thin lines, thick for covering large
surface areas.) I wait until it is almost but not completely dry, a
minute or two, then scratch designs into the paint with a scribe or
exacto. If I wait till the paint is too dry, I don’t get crisp lines
and the paint tends to fleck off. If I dont’ wait long enough, the
paint is too wet and oozes into the lines I have just created with
the scribe. Anyhow, its a fun and simple process. Hope this info
helps. Electrical tape as a resist also works…

Chelsea Stone
Eye Candy Jewelry
Prescott, AZ


#7

I wrote about using ImageOn for etching in my last post and after
reading some of the other descriptions I would like to add that
ImagOn is fairly simple to use. There are several steps, but it
basically is not difficult and has superb results. The chemicals used
can be bought easily in stores/garden shops- ammonia and soda ash
(sodium carbonate) which is used for pools- PH plus. Don’t confuse
that with Sodium bisulfate which is PH minus used for pickle.

When you order the ImagOn from Daniel Smith Art Supply Store in
Seattle, they send the directions. Follow them carefully and you
should get some of the best results possible; the detail is amazing.
(the product is used for printmaking) With careful light exposure it
works every time. You can get rid of all those pens, asphaltum and
all the rest of that stuff.

Cheers,
Louise


#8

Not sure what kind of “kit” you are using. But I know there’s been
a recent flurry amongst enamelists about the “Imagon Ultra"
photopolymer film that is supposed to be an excellent resist for
copper in order to achieve detailed clean lines for etching. It’s
the reverse of PnP blue in that it is for intaglio etching – where
the black lines are what get etched. There is an enormous amount of
info about this at www.polymetaal.nl (they go into great detail
about techniques, etc.) go to their page on intaglio etching –
resists and transfers. They give you the complete “how to” guide.
I also know this is available from Daniel Smith art supplies. You
can also purchase just the resist from Thompson Enamel
www.thompsonenamel.com look under “what’s new” As far as
mordants go, I don’t know of much else for copper other than ferric
chloride, but I think Dick Blick Art supplies sells something call
"copper etching solution” Might want to check with them about that.
www.dickblick.com If anybody has results to report about their
experience with the Imagon Ultra resist – I would love to hear
about it since I have yet to try it – but heard it works pretty
well. Kelly @kelly_luttrell


#9

The problems you have are due to the nail polish being too hard and
brittle. I have successfully used permanent felt tip marker pens but
you do need to use the fat type which will put a lot of ink on the
metal in one go - you can’t go over the area again as that lifts off
the original ink. You can make up a good resist using shellac and a
flexible resin like gum lac or gum tragacanth dissolved in methylated
spirit (Stoddart solvent) and I usually colour it with a spirit dye
so you can see where it has been applied. If you are trying to
achieve a deep etch, you will find you have problems with
undercutting of the metal and, in severe cases, this can destroy the
clean edge of the etch by etching down, sideways and then up again so
removing the metal under the edge of the resist. In the printing
trade where this used to be a particular problem they used ‘Dragons
blood’ to prevent it. This is a red powdered resin which they dusted
over the plate part way through the etch and then heated the plate
so that the resin melted and coated the sides of the etched area
before continuing the etch the plate.

The normal ferric chloride etchant is as good as anything but it is
much more effective if you use it in a bubble tank as it is
imperative that you continually remove the fine iron dust which is
formed by the etching process from the etching areas. The tank need
be no more than a waterproof container big enough to take the work
with the pipe from a small fishtank bubbler held in the bottom of the
tank. I use a length of thin plastic pipe with a number of small
holes made along the length of the tank.

Best Wishes,
Ian
Ian W. Wright
Sheffield UK


#10

I recommend fingernail polish as a resist. Holds well, lasts, and
easy to cleanup. Good Luck. Mark


#11

I do a bit of etching on copper bowls and sculptural pieces. These
are rarely flat, so a lot of the resists, like the ones used to make
plates, don’t work for me. I’ll share some of my favorites:

	1.   Nail polish.  You can apply it right out of the bottle, or you

can thin it slightly with acetone (nail polish remover). If the metal
is very clean (I wipe it with a cloth dipped in ferric chloride and
rinse well), you can get very detailed lines and tight edges. Pick a
color that will stand out against the copper. I like “Wet N’
Wild”… it will take the abuse of high school girls, and will even
stand up to sandblasting! I will often etch, then patinate the metal
without removing the resist. The downside to this resist is that you
have to remove it with acetone, so you need GOOD ventilation.

	2.  Rosin.  An engraver at the US Mint turned me on to this one.

Just dissolve a bit of rosin in a small bowl with a little alcohol.
Paint it on with a fine brush. You can scratch VERY fine lines into
it, without chipping the edges. This is what is used on the steel
plates that make our currency and stamps. It will go on almost
transparent. I use it to develop a frosted background against a
polished surface. It won’t take a strong, violent etch, since heat
will cause it to lift, but a slow etch works GREAT. Ferric chloride
on copper, nitric on silver, aqua regia on gold. Just dip it in
alcohol (or wipe it, if it’s a large piece), and the resist comes
right off.

Check out Kelvin.com for etching supplies. They sell "educational

materials" to schools, so they have products that are safe for home
use. They sell ferric chloride, and the etching pens, as well as
other resists and transfers.

I always wear rubber gloves, a rubber apron, and face shield when

etching. I have good ventilation, and often work outdoors to avoid
breathing fumes. I neutralize spent acids with baking soda before
disposing of them. Safety is a good practice…

Doug Zaruba


#12

I have posted a lot on this before, but here are a number of web
sources on etching. Some are particularly for copper-- all will work
on copper. Some of these are just chemical based but there is a
little here on Electrochemical processes which can work a bit
faster. To avoid too much undercutting faster is better. All
resists will undercut. It is more a function of the mordant and
mordant concentration. The ferric chloride mordant etches copper by
reducing iron which clogs the etch zone and slows the etch not
removed as it forms. Agitation putting the etched surface down and
the use of chelating agents( Edenburg etch) help control this.

http://www.glass-on-metal.com/pastart/etchingoptions.htm
http://www.polymetaal.nl/beguin/mape/edinburgh_etch.htm
http://www.enamellers.nl/english/electrolyse.htm
http://perso.club-internet.fr/gravert/galvetch/index.htm
http://www.oldschool.u-net.com/etch.htm
http://www.geocities.com/pdmtr

Printmaking and printed circuit manufacture uses a lot of etching
so you can get a lot of by searching these areas.

jesse


#13
        If you are not etching your copper upside down, give it a
try. In an Arrowmont workshop (sorry, can't remember which one) we
taped masking tape to the back side and laid the piece on fiber
scrubbies (supermarket) in Pyrex dishes. The sludge that forms can
than fall out. This results in a cleaner etch. 

Marilyn, I like the idea of fiber scrubbies - When I learned to etch
in class we used a plastic shoe box to contain the ferric chloride,
then put tape on the back of the piece to be etched and suspended it
in the ferric chloride by extending the tape to either side of the
shoe box. I also read that the copper to be etched could rest on
two pieces of sytrofoam as well. But in any case, we also always
suspended the item upside down. Works great for me. Kay


#14

Chemical etching of copper; etching resists

Excellent etching tips here recently! Special thanks to Karen
Christians for her very complete protocol. I agree about Penny
Brite! Love the stuff-thanks for the source-I’m running low, and
couldn’t remember where I bought it last. I use it too as a
pre-patina clean. before liver-of-sulphur or heat-coloring.

Can I use the transparency film in my computer laser printer, rather
than using a photocopier? Is there anything different about laser
copiers as opposed to laser printers? The local copy shop is very
unfriendly and hostile about things that aren’t standard paper
copies.

I know there’s a lot of different resists out theRe: suitable for
different applications. If you want to draw your designs into the
resist, I still like the traditional printmaking etching resists. I
was a printmaker before I was a jeweler (I should have known what
was in my future, when I cared more about the plate than the print).

“Hard ground” is for drawing into: you can achieve wonderfully fine
lines. I use it for calligraphy. It does not chip, unless you’re
really rough with the edges. Easy to apply with a brayer (the cheap
4" blockprinting kind). Pour some into a pie tin, roll, roll, coat
the metal. It “sets up” quickly enough to apply 3 coats in several
minutes. It’s sort of waxy. It does not have to be totally opaque.
Let air dry overnight, then draw. It dries out slowly enough so
there’s no rush to finish the drawing. 2-3 days, it’s still ok.
Think of all those complicated etchings you’ve seen with millions of
lines: it took time to make all those. Those printmakers were using
a “take-your-time, get-it right” resist like hard ground. Mistakes
or scratches can be fixed with red stop-out varnish, which is
fast-drying and alcohol-based. On a curved surface, use a brush to
apply the ground, but it’s much harder to get an even thickness.
Don’t use it for the back of the plate, where you need to stick the
tape that will hold it in the mordant. (Also, don’t use water-base
stop-out varnish! Pinholes galore.) After etching remove ground with
mineral spirits. Very sloppy but not difficult to remove.

Soft Ground is for impressing a texture into. I’ve never tried this.
I have a rolling mill for that.

There’s a harder ground too, that has to be melted on, with a
hotplate underneath. I don’t recall what that is for: I think really
fine lettering.

There is a thinner, paint-on ground, called “Jane’s Ground” that is
wonderful for painting fine details. But I got mine from someone
else, and now can’t find the source.

Asphaltum is sticky and messy, in my opinion. I find it harder to
draw into, more prone chipping when it gets too dry. Asphaltum is an
ingredient in hard and soft grounds. The grounds are more like a
cross between tar and wax: tar to stick and wax to dry.

Graphic Chemical in Villa Park IL is a major supplier: you can buy
direct or through an art supply store.

Enjoy!
Lin Lahlum


#15

I’m a bit behind in my Orchid reading, but will add my two cents
worth on using nail polish. My experience is to buy the cheapest nail
polish and avoid any with ‘teflon’ added (usually more expensive). I
found that type tended to lift up along the edges of the scribed
lines. Sandra


#16

A student of mine suggested floating pieces of metal upside down in
the etchant taped to stryofoam. It works great and allows for several
pieces to float in the etchant at one time. I recommend the dense
blue or pink stryofoam rather than the beaded white stuff. I cut up a
large piece of blue foam into a variety of sizes and wash them
carefully after using them. I seem to be able to reuse them
indefinitely (at least 3 years now). I tape the metal onto the
styrofoam using tan packing tape. when teaching a class students can
put their name on the back (top) and the time they put it in the
etchant - helps everyone keep track of their work. Sandra


#17

Back again Anyone interested in ferric chloride etching should
search “Keith Howard” and words like “non-toxic etching”. Keith is a
printmakers who seems to know a lot about ferric chloride. One idea I
got from him is to use a liquid acrylic floor wax as a “hard ground”.
He suggests adding india ink (I’ve added acrylic paint) so you can
see it against the scratched metal. It’s good for doing 'intaglio’
type etching - i.e. fine lines. But you can also paint it on with a
brush. One thing that seems somewhat critical for success with this
is to sheet on the wax and let the metal sit vertically (so most wax
drips off leaving a fine layer of wax) and scratch through the wax
with a scriber after about 20 minutes. If it gets too dry the edges
seem to lift off - so the 20 minutes seems important.

Someone mentioned not using Sharpie pens. I agree. I use Staedtler
Lumocolour permanent markers in the transparent colours (red, blue
etc - NOT black).

By the way, I am scheduled to teach a married metal and etching
course at Metalwerx in Boston this summer, if anyone would like to
learn more. I also have notes on my website on etching with ferric
chloride. It’s a technique I love. Once you try it, you get hooked.
It’s also a great technique to teach to beginners as the results are
always impressive.