DIY Acid Etching on Metal for Jewelry Making - Part IV: Etching on Silver Using Ferric Nitrate

Part I of DIY Acid Etching on Metal for Jewelry covered how to transfer designs on metal.

Part II and III covered how to prepare an acid etch bath for copper and brass.

In Part IV, the same techniques apply for etching on silver, except the acid is different.  Please review Part I - III to help understand the basic etching process.

Here’s my unscientific method for etching on silver, plus how you can avoid making the same mistakes I did.

Part IV: DIY Etching on Silver for Jewelry Using Ferric Nitrate

Ferric nitrate provides a clean etch on sterling silver and fine silver.

You can buy ferric nitrate crystals at most chemical supply stores. I buy from Adchemco Scientific in Tucson, Arizona. ($60 for 5 pounds of crystals. Smaller quantities available for less $$$).

If you order ferric nitrate from an out-of-state supplier, the cost will include shipping and HAZMAT packing costs, so try to find a local supplier to save $$$. (When I was an ASU student I bought it through my local University Chemistry Store, but 9-11 may have changed that.)

Ferric nitrate crystals look like lumps of sugar with a light hues of purple. Ferric nitrate crystals should be combined with distilled water, but I confess, I use tap water and have not had any problems.

You may have more minerals in your water supply that could make a difference, but I apologize in that I haven’t researched those variables. So, to be safe, jot down “distilled water” on your grocery list and have it handy. 

When it comes to a recipe for mixing a ferric nitrate solution, I have done a bit of research and experimenting. I found that a 50/50 mix works well. So, you don't need to buy a gram scale if you don’t have one.

By now, you may be thinking, "She probably adds a “pinch of this” and a “dollop of that” when she cooks, rather than following a strict recipe." Very true! I'm attempting to show where you can cut corners and where you must be careful.

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Note: Please do not confuse ferric nitrate with ferric chloride. Ferric chloride works well on copper and brass, but does NOT work on silver.

Ferric chloride and ferric nitrate are corrosive iron salts. Although they are potentially harmful chemicals, they are much safer to use than acid. They do not have noxious fumes and are not absorbed through the skin. They will stain skin, counter tops, and clothes, so wear gloves, protect your working surfaces, and wear old clothes when etching.

To be safe, please read the precautions listed in the Goss Studios article on etching, sent courtesy of Art Chemicals.com. I have never experienced fumes or flammability, as mentioned in the article and am not cavalier about handling chemicals, but feel that some precautions are overkill.

I smile when I see a warning on a paper coffee cup: “Caution, hot liquid may cause severe burns.” (OK, I can see the steam - I get it. :  )
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Here is the link to the formal recipe for etching on Silver, sent courtesy of ArtChemicals.com. The article is written by Goss Design Studios.

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Goss Design Studios - Ferric Nitrate Etching Recipe
400 ml of distilled water
300 grams of Ferric Nitrate

Always add crystals to water!
NEVER water to crystals.

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My Unscientific Etching Process:

Fill a quart size (glass or plastic) measuring pitcher with 2 cups of tap water. Slowly add enough ferric nitrate crystals (about 2 cups) to make a total solution of 1 quart. Mix carefully with a wooden or plastic spoon (do not use anything metal) until the crystals are dissolved. The solution will turn a dark greenish color that is fairly clear compared to the thick, opaque, greenish ferric chloride, which is used straight out of the bottle. (I feel like I should be chanting a "Spell" while stirring, as it reminds me of a Witch's brew. : )

The instruction from Goss Studios says to “kick start” the solution with “a teaspoon of old, 5:1 diluted, nitric acid solution.” I skipped that. I have worked with nitric acid and it is very dangerous stuff. I avoid it whenever possible. If you are more daring than I, please try the Goss recipe. It may increase the strength of your ferric nitrate solution. I'd love to learn about your results.

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Note on Nitric Acid Etching: 

An accepted way of etching silver is to use nitric acid. I tried etching silver, using 3:1 nitric acid solution, and was very disappointed in the results. The acid quickly corroded the dry toner design and red Staedtler pen resist. The edges of the design came out fuzzy. The fumes were so bad that I decided it was not something I wanted in my studio.
However, many professional jewelers swear by it as a clean etch method. They use a stronger resist, like asphaultum, which I find messy and hard to work with.

I calculated that it costs less to use nitric acid than ferric nitrate, as it lasts longer and a smaller amount is required per etch.  Nitric acid concentration gets stronger as the water evaporates, unlike ferric nitrate, which is weakened by moisture.

It is necessary to follow safe OSHA disposal requirements.  You can get more info on nitric acid etching on the internet.
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You can etch about 20 pendant-sized pieces of silver in a quart solution of ferric nitrate before it starts to slow down and finally exhaust. I calculated that (in a perfect world) 5 pounds of ferric nitrate, at $60, should produce approximately 100 etched pendants at a cost of 60 cents per piece, just to etch.

This technique is better for creating your own special unique, one-of-a-kind designs.  This may not be an economical way to create a wholesale line of jewelry. There are more economical ways of producing a jewelry design that appears to be etched, such as having a wax model cast by professionals.

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This photo shows the original 4 inch x 2 inch, 16 gauge, piece of sterling silver intended to be a bracelet.
The design has been "ironed on" and the edges filled in with red Staedtler pen resist.  The back of the silver is covered with clear plastic packing tape as a resist to the ferric nitrate.

The transfer design was made with of a sheet of IBM transparency acetate copied on my dry toner copy machine.

The copy machine transferred a thick layer of dry toner (dark black lines) on to the acetate.

The acetate was then placed (toner side down) on the squeaky clean piece of sterling silver. I put a piece of paper towel on top of the acetate.  I placed a hot iron on top of the paper towel (for about 3 minutes) this heated the acetate and melted the dry toner on to the silver.
When the hot metal cooled enough to touch, it was placed in a glass jar of water. The acetate popped off easily, leaving the dry toner design on the silver.

I used a red Steadtler pen to touch up a couple of places that didn’t transfer fully to the silver.

The outside borders of the design were filled in with red Staedtler pen as a resist to the acid.

HERE IS WHERE I BLEW IT!

A 50/50 solution of ferric nitrate takes twice as long to etch silver as ferric chloride does to etch copper and brass.

CAUTION:   Don’t be blasé about it. I learned the hard way. Below is a photo of a nice, thick piece of silver I was etching for a bracelet. I got involved in another project and lost track of time. It was in the etch bath for 6 hours and the ferric nitrate etched holes all the way through the silver in some spots. I was miffed at my neglect (and material loss), but it was a valuable lesson. I was pleased to see that the dry toner resist held up very well the whole time. The red Staedler border ink mask did break down somewhat.  I should have taped it, but I didn't think it would be etching for 6 hours!

Since then, I always carry a loud alarm timer set for 30 minutes as a reminder to check on the etch bath. (Fortunately, I was able use the middle section of the design, so it wasn’t a complete loss. And, you can always send silver (mistake) scraps to a refiner in exchange for a $$ check.)

The back of the silver sheet was covered with clear packing tape to protect it from etching. So the etching came from the front side of the piece.

The clear acetate shows how well the dry toner melted onto the metal. Only a few spots of the black dry toner are left on the clear acetate. Most of the dry toner melted on to the silver nicely.

In case you place the iron on the design too long, delicate lines may run together. So it might take a bit of experimenting to see how long it takes to melt the toner and still retain crisp design elements.

You can always start over if the toner smears or doesn’t transfer completely. Just clean off the metal with acetone (or alcohol) and begin again. No loss.

You’ll get the hang of it after a few tries.
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Summary of Etching on Silver:

THE DESIGN

a.) Draw your design directly on silver using a red Staedtler pen.

 b.) Or, use Future clear floor wax (or fingernail polish) as a resist. Scratch out a design through the resist. You can also use tape as a resist to block off areas.

c.) Or, draw a design on paper, then scan it, resize it, and save it on Photoshop using the darkest black / white contrast available.

Print out the design in highest resolution possible.

d.) Make sure any lettering or numbers in your design are “mirror” image, so they “read right” when transferred to the silver.

e.) Copy the design at a photocopy store (or use your own copier) on a machine that uses dry toner. Set the copy as dark as possible to achieve a thick layer of dry toner on a sheet of heavy magazine paper or acetate transparency.

f.) Cut out the dry toner design copy leaving a ¼ inch margin around the perimeter.

DESIGN TRANSFER TO SILVER

a.) To recap - Layer design, silver and paper towels, per diagram as shown:

(Make sure your flat workspace is not harmed by the heat of the iron. I have scorch marks on my dining room table!  An old desk or wood table works well. Must be completely FLAT. An ironing board does not work.)

b.) Heat an old iron to hottest setting. (Note: A newer, expensive iron that has an “automatic shut off” won’t work.)

c.) You can use an old electric skillet, set at 350 degrees, just reverse the order of the diagram above so the silver design is facing up. Use something very flat and very heavy (an iron?) to lay on top of the design. Don’t wiggle it when you remove it or it may smear the melted toner. It helps if the weight has a handle so it can be lifted straight up easily.

d.) The iron (or skillet) remains in contact with the silver until the dry toner melts on the metal.
Note: The time may vary depending on the thickness of the silver, depth of toner and heat of the iron (or skillet). You can hear the iron and the skillet thermostats clicking on and off to maintain the temperature.

e.) When you lift the iron off the metal, don’t remove the paper (or transparency acetate) from the silver. Let it cool down slowly.  When it is cool enough to touch, carefully pick it up by the edges and drop it into a glass jar of water. When it is cool, you can pop off the transparency acetate or soak off the magazine paper, leaving the dry toner layer that has melted onto the silver.

f.) Tape off areas of your design (such as the back) that you do not want to etch.

g.) Attach silver (dry toner side down) to a piece of Styrofoam, or a piece of plastic bubble envelope, so it will float (like a flat bottomed boat) on top of the ferric chloride etch bath.

THE FERRIC NITRATE ETCH BATH

a.) Using a plastic or glass container, wide enough to accommodate your silver “boats,” mix 50:50 solution of ferric nitrate. Container can be shallow in depth since the silver will be floating on top of the ferric nitrate solution.

Make sure your ferric nitrate container is sitting on top of, or beside something that vibrates, (Part III refers to dryer or aquarium air pump) to help move the etched particles off the metal.

b.) Set timer for 30 minutes and lay the silver “boats” on top of the ferric nitrate solution.

c.) Check every 30 minutes for level of etch you wish to achieve for your design.  (I admit that sometimes I quickly stick my fingers into the ferric nitrate to pluck out a floating boat, and all it does is stain my fingers a bit.  If washed off quickly, no stain on skin, but sometimes need to soak fingernails in weak bleach solution to remove the stains later that night.)

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Note: I found it necessary to rinse off gunk that accumulated on the design side of the silver "boats" every 30 minutes or so.  This was not necessary for etches on brass and copper using ferric chloride. 

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Also check for any missing areas in your design that may have deteriorated. You can rinse off the ferric nitrate and repair missing areas with red Staedtler pen if needed. Then return to acid bath.

d.) When design is etched to your satisfaction, remove from ferric nitrate and place in separate solution of 3 TBL baking soda and 1 cup water. When the solution stops fizzing, remove the silver and rinse thoroughly in water.  Remove all tape and rinse again. 

e.) Make sure you put a secure (plastic) lid on the ferric nitrate solution.

Admire your etched design!!!

DIY- Design Transfer for Acid Etched Brass, Silver and Copper Jewelry

What is your favorite design?  Wish you could transform it into a series of etched pendants? If drawing multiple designs by hand would take hours, here is speedy way to transfer complex designs to metal for acid etching.

First, scale the design to the exact size you need.  You can do this on your computer, or you can go to any photocopy store to reduce (or increase) the image size. Make sure you have a flat design with strong black and white contrast areas. (Shaded, or gray areas, won't work.) The design must be black and white. 

Above (left) is an example of a design that can be used as a positive or negative image.  (You could reverse the design via the "invert" setting on your computer in Paint.net or PhotoShop graphic application.)

While you are in the Copy Store, make a few copies of your designs on a copy machine that uses dry toner.  Make each copy as dark (bold) as you can.  The layer of dry toner that is transferred from the paper copy to the metal acts as a "resist" to the acid.  Below is an example of brass that was etched using ferric chloride.

In acid etching, the black design areas act as a resist to the acid, the white design areas will be etched deeper than the black design areas. Generally, the etched (white) part of the design can be thought of as the background.

If your design has any letters or numbers, make sure you make a "Mirror image" so the words will read right when you transfer them to the metal.  Here is an example of a name plate for a key ring.  In the design (above right),"Nikki" is a mirror image that will read correctly after it is transferred to metal. (below left)

If you have a copy machine at home that has a dry toner cartridge, it should work fine.  But do NOT use an ink jet printer.  Ink jet copies won't transfer.  I have an old Canon K140 copy machine that uses dry toner.  You should test other dry toner copiers before you buy one to make sure the toner transfers well.
 

The best transfer paper is free.  Save your old magazines and use them as transfer paper. (You can also use Sunday newspaper magazine section, but if the sheets are too thin they may get stuck in the copier).  The heavy paper from a fancy magazine works best.  Regular copy paper doesn't work.


You can "gang" your designs on one sheet of paper to transfer multiple images on a single sheet of metal.
I know this sounds strange, but trust me, only the dry toner from your paper copy will transfer to the metal.  The print on the magazine page won't transfer.  Think of the magazine paper as a "carrier" for the dry toner. And, isn't it great that we can recycle the magazine paper while we are creating something new and beautiful?

Set your designs aside and prepare the metal for transfer (Bronze, Brass, Copper, or Silver).  The metal needs to be spotlessly clean.  Bar Keeper's Friend  is a powdered cleanser (with oxalic acid) that works well to clean off any oil from fingerprints and tarnish on the metal.  It also roughens the surface enough to help grab the dry toner.

The most important step is to make sure your metal is meticulously clean and the water sheets off evenly, without any spots.  If your metal has even the tiniest bit of dirt or oil, the toner won't adhere to the metal.

Next, find a flat work area near an electric outlet where you can plug in an iron and press the dry toner paper onto the metal.  Use your regular iron in dry setting (not steam), and turn it up as high as it will go, (usually Cotton setting).

Press down on the iron to make sure the paper design makes good contact with the metal. (If you wish, you can place a piece of paper towel between the iron and the paper design to keep the bottom of your iron clean, but if you do it right, your iron won't pick up any of the dry toner.)

Let the iron set on top of the paper design for at least 2 minutes.  Don't rush it and don't move the iron, or it may smear the dry toner before it is set.  (Leaving it for 5 minutes will work as well, if not better.)

Next, carefully lift the iron up and turn it off.  Let the metal and paper transfer cool on its own.  When the metal is cool enough to touch, put it in a bowl of water to soak off the magazine paper.  Don't rush it.
 
Let the paper get thoroughly saturated.  After the paper is softened, you can rub it off with your thumb and the toner will remain intact.  Don't worry if some of the paper is attached to the toner.  It will dissolve in the acid etch bath.

If you don't want to use your iron, you can use an old electric skillet.  In the center of the electric skillet, layer the design paper (right side up), then metal, and on top of the metal, place a brick to press the metal onto the paper design.  Heat your electric skillet to 350 degrees for 2-3 minutes. Turn it off and let everything cool gradually before you remove the metal.

In some cases you can touch up any missing spots with a special type of felt pen, but the entire design etches best if the resist is uniform. 

In case you find that part of your design didn't transfer properly, (maybe there was a bit of oil on the metal?) you can remove the dry toner with acetone and start over.

If your design didn't transfer fully, you may want to increase the length of time under the iron or skillet.  5 minutes may work better as some iron temperatures may not be as hot as others.

Now, you are ready for the etch bath.  We'll cover that in detail, in future articles.

 This is the first in a series of 4 parts about acid etched designs on brass, copper and silver.  Next, we'll cover how you can draw designs, by hand, on metal, using a special felt pen as a resist. 

Stay tuned!

"Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did do. So throw off the bowlines. Sail away from the safe harbor. Catch the trade winds in your sails. Explore. Dream. Discover." — Mark Twain

**** Here is an IMPORTANT update to this tutorial on 4/1/2014:  In the past couple of years, the composition of dry toner has changed drastically and may not work with this method.  The reason being that copy companies have gone "green" and changed the formula of the toner.  This new "green" toner is not working for transfer designs.  If you have been frustrated using this method, fear not!  There IS a solution!  

Find a copy/printer that uses toner with the highest content of IRON as possible.  I found dry toner cartridges (MICR) that are used for printing checks have a very high content of iron since they must print checks that work with magnetic security systems.  So, look for MICR toner cartridges and make sure they work in your printer.  Their website will let you know if a MICR toner cartridge is compatible with your copy/printer.

Do what you enjoy!

Virginia Vivier

Esprit Mystique Artisan Jewelry

Esprit Mystique Etsy

Tucson, Arizona