Etching Metal Part 1: The Resist

This three part post on etching is in conjunction with my upcoming demo for the Metal Clay Artisan Guild in Connecticut.

I have been working in metal for almost two decades and it all began with etching.  During a printmaking class in high school I learned to etch zinc plates with Nitric Acid for intaglio printing and fell more in love with the surface qualities I could create in the metal than the final prints.  I have used these basic techniques for years in my own work and in my classroom.  From printmaking, to sculpture to jewelry, the technique is relatively the same, it just varies in size- also, today I have found safer materials to work with than nitric acid and asphaltum.  The information in these next two posts is what I use to successfully etch copper, nickel and brass metals.

1.  Prep Your Designs & Your Metal

Start by figuring out what you will eventually use the piece for.  Will it be the actual piece of jewelry? Maybe it will be a stamp for polymer work? Maybe it will be a plate for embossing paper?  Or maybe it could even be a texture plate for metal clay?  In any case, you want to determine your size and draw or print the original artwork or copyright-free image you are using the exact size and shape you will eventually etch.  The cleaner and sharper your image is, the better it will work in the end.

Prep your metal by first cutting it to a size slightly larger than the design you want to etch, it also must be flat.  Next, clean it with a super fine steel wool pad to remove any oils that might disrupt the resist or the etch.  After this point, be careful not to touch it with your fingers, only hold it by the edge.  Immediately before you apply any of the below resists, wipe the piece down with rubbing alcohol.

2.  Create Your Resist

You will need to create a "resist" on the surface of the metal to protect the part of your design you would like to keep raised.  The etching process removes the metal that is left exposed.  You can etch sharp clean lines or large backgrounds can be removed.  This needs to be decided during your design.   There are many ways to create a resist on the metal, here are three simple and safe materials to use as resists.

PnP Resist (Press-n-Peel blue acetate film)

If you have a very precise image or are trying to transfer a photograph, one of the best ways to get your image on the copper is using PnP paper.  You can photocopy your image to the matte side of the PnP paper using a copy machine with a carbon based toner.  In my experience, printer ink does not generally create a successful resist.  You will then iron it on to the metal with the matte side facing down to create a resist, as you iron and the image becomes more and more visible through the acetate, the resist is transferring.  When the metal has cooled, pull up a corner of the PnP to check your design, if you need to you can lay it back down and keep ironing.  If there are small areas that need to be touched up, you can fill them in with black permanent marker or nail polish.  You will need to protect the back of your design with contact paper or electrical tape and then seal the edges with nail polish to prevent them from being etched.

There is a great article on PnP you can find on the Ganoskin Project site that you can follow a link to here.

Tips for PnP Resist:

-Run the copy machine until you can get the darkest (and cleanest) copy possible on white paper before copying on the matte side of the acetate.

-Be prepared to test your iron on scrap metal.  Since every iron is different, you will need to have some extra PnP and scrap metal to do test strips.  My iron at home requires the highest setting for almost 10 mins to get the small size transfers in this post, the iron in my classroom requires a lower setting and less time.  Begin on your highest setting and move the iron in circles until the image becomes clearly visible or the acetate buckles.  If it buckles, turn the iron down.  Hold the acetate with tweezers down in one corner and peel up with another pair of tweezers from another corner to check transfer.  Continue ironing as needed.  I generally time my test strips in 3 minute increments.

Tape Resist 

Using either masking tape or clear plastic packing tape, make a "tape sandwich" with your metal in the middle.  Make sure to seal all the way around the edge, this will stay in place during the etch to protect the back and sides.  Rub the tape down to remove any air bubbles. Then either draw or tape your design on top of the tape, leaving a border of tape to protect the edge.  You will then use an exacto knife to cut out your design.  In this case, I am cutting the design and removing it in order to etch the lines of the designs.  The tape will be left on the background area to protect it.

Permanent Marker Resist 

Choose a high quality permanent marker and draw your design directly on the clean metal.  Make sure it is a rich, solid black with no transparent areas.  Make sure there is a border to protect your edge and seal your back with either electrical tape or nail polish.

Aquatint Texture Resist

The same technique used to etch printmaking intaglio plates to create a stippling effect is great to create a texture background to hold a patina.  You can either use it to create a simple texture piece or in the background of any of the above resist methods.  Simply spray a mist of spray paint LIGHTLY across the back of the piece of metal in a quick sweeping motion.  This should leave "dots" randomly across the surface.  Experiment with the density of the spray and the effect you get from the etching, this is another time you will need to do test strips to get your desired effect.  Here, I drew an image with permanent marker and "swept" it with spray paint to create the dots in the background which will be our texture later on.  You can see how light it is, the darker it gets, the more you are blocking out the etch.  Don't forget to protect your edges and your back.

If you want to learn more about etching methods in printmaking, check out the great site artist Julie Niskanen has on intaglio process by clicking here.

3.  Etching the Metal

Once you have prepped and applied your resist to the metal, visit my next blog post (here) to learn how to complete the etching process.

Same Technique, Different Sizes...

All of these pieces were done using the etched copper method in this blog post.  These were all specifically done using a masking tape resist, as described above.  From the 6' long hanging sculpture (right) to the 14" x 18" framed etching (left) to the chunky cuff bracelet (above), the same method has endless possibilities.

  

Repoussé Effects in Metal Clay

Repoussé is a traditional metalworking technique where a raised or relief surface is created on the front of the metal by hammering a design from the back of the metal.  It is a french term whose origins mean to push from behind.  It is often used along with another traditional technique called "chasing" where the design is then sharpened or refined from the front by sinking in the metal on that side.  The effect of repoussé and chasing creates what is often referred to as embossing.  You are dealing with the elastic qualities of a malleable metal, so there is no actual loss of metal. 

This is a relatively simple technique to replicate in metal clay while the material is in its clay state.  It is a great way to incorporate original designs and textures, even for the beginner artist.  You will need something to create your impression with, the pieces in this post were done using scratch foam, so that is the process I will focus on here.   Scratch foam is a popular and economic material used in basic printmaking.  If you think it is an elementary school material, check out the sophisticated prints by artist Annette Mitchell who is able to get woodcut-like imagery from recycled meat trays.  If you can not find it at a local craft store, you can always use cleaned foam trays from the supermarket.  Just cut yourself a square to work with.

Begin by working out a simple design.  I did a series of pieces based on swirling cloud patterns, they all began with the same frame, but I played with the interior a little differently on each piece.  I like working out designs like this on tracing paper so that I can quickly replicate elements I am happy with.  I then tape the tracing paper to a piece of scratch foam and lightly go over it with a ball point pen, just enough to get a slight indent in the surface.  I then use an embossing tool to go over the lines, but maintain medium to light pressure.  Each time the lines will become more pronounced, but I don't end up ripping or wrinkling the foam.  As the lines get deeper, I change the gauge of the embossing tool if I want thicker lines.  The key is patience until you get a feel for the right pressure on the foam.  If you are looking simply to create texture sheets to emboss with, you can use anything you can dent the surface with from a comb to a meat tenderizer.  Keep in mind the scratch foam has a more "smooth" side and a more "rough" side, you will need to look closely at the foam to discern this, I recommend carving into the smooth side.  In any case, the surface of the clay will pick up the surface of the foam, which is more subtle on one side than the other.  

Once the design is carved in the foam, I lube the foam so the clay will eventually release.  I set my rolling slats (or cards) on top of the foam on either side of the design a little thicker than I want the piece to account for the raised areas.  If the piece of foam is too small to support the width of the slats, I lay additional slats (or cards) next to the foam to keep them even.  I then roll my clay into the design the same way I would roll it onto any other texture plate.  I then gently pull it off and trim the excess.  Once dry, they are fired and finished the same as any other piece.  The bonus of the scratch foam is that it is relatively inexpensive and fairly forgiving.

A few tips about scratch foam... 

If you chose the wrong side and this impacts your design (which you will be able to see as soon as you pull it off) simply smooth  your metal clay piece with a damp sponge - as long as you are light with your pressure it will clean up the surface without removing the embossing.   Also, remember this is a printmaking process - you are essentially creating a "stamp" that you are embossing your piece with so your design must be the REVERSE of what you plan.  In a symmetrical design this does not matter, but in the design of a piece like I did here it can make a difference.  I planned it backwards because I have done this enough times to think about it that way.  If you are not quite there yet, this is another good reason to workout designs on tracing paper, because you can then lay them on the foam on either side.  If you draw your design exactly the way you want it, you should then lay the tracing paper face down on the foam.  It will reverse the design on the foam and come out the way you intend in the clay.  Since it's tracing paper, you can see through it and can still easily trace it.