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Etching Copper and Silver using PnP Blue Paper


Etching is one of those things I've been wanting to try for a long time. As is my wont, I bought all the materials and let them languish in my workshop for some time. Who knows when I would have gotten around to doing it if I had been left to my own devices, but a commission for an etched bunny ring forced my hand and I'm so glad it did.


For some reason it just seems very complicated when you read about it, but actually it isn't at all. You need a few tools, but most jewellers will have the basics already. To use PnP paper, however, you do need to use either a black and white laser printer with a toner cartridge that contains oxide-based toner, or a photocopier with the same type of toner. Inkjet printers unfortunately won't work with this technique. My printer is a fairly old HP black and white laser (about 12 years old I think - ancient in computer terms!) and it works well for this.


Here's a little list of things I used whilst etching:


Ferric Nitrate - for etching silver

Ferric Chloride - for etching copper

De-ionised water (you can buy a 5ltr bottle from Halfords - it's used in household irons and car batteries)

Iron

Flat piece of tile or marble

Hotplate

Rectangular Pyrex dish with lid (or other suitable sealable container)

Plastic gloves

Apron

Eye protection

PnP paper (Press n Peel Blue)

Nail Polish

Acetone (nail polish remover)

Cotton

Sellotape

Stick-on vinyl

Teaspoon / Burnisher

Sealable bottle for waste chemicals

Kitchen roll

Bicarbonate of soda

Plastic tweezers

Small scrubbing brush

Two small plastic bowls (you can recycle old takeaway tubs)

Copper or silver

Laser printer with iron-containing toner cartridge



The first decision to make is whether you want to use copper or silver to etch onto. My first etch was onto a tiny piece of scrap silver, but using copper makes it much more affordable to experiment and create larger works. This blog will focus mostly on etching copper, but the principles are similar.


Metal Choice


I bought a couple of piece of 0.8mm 6" x 6" pieces of copper from eBay to start with. I wondered whether 0.8mm was too thin to etch with, but it worked well. If you want to form your etched pieces I would use thicker copper. I tried to create a cuff with a 0.8mm piece and the cuff tended to crease where the metal was etched heavily. I have since bought some 1.5mm thick copper and will let you know how it goes. I would also use thicker metal if you wish to enamel your pieces later as the thin metal is easier to warp which will crack your enamel.


Choice of Etchant


To etch silver you need to use ferric nitrate, whereas to etch copper you need ferric chloride. I remember it because both 'copper' and 'chloride' begin with a c.


I bought the ferric nitrate as crystals from Vitrum Signum in the UK which I diluted with de-ionised water (available from Halfords in the UK). The dilution rate is approximately 400ml de-ionised water to 300g ferric nitrate crystals.


The ferric chloride came as a ready-made brown solution from eBay.


Etchant Precautions


Although neither will immediately burn your fingers off if you dip them in either solution, this can lead to a false sense of security. They're not great chemicals, so the usual precautions should be taken. Wear goggles, an apron and plastic gloves. If you get any on your skin wash it off as soon as you can, and if you get any in your eyes be extra careful and wash thoroughly. Also, don't mistake it for your coffee and drink it. As someone who once took a sip of the paint water I wash my watercolour brushes in, this can be risky! You shouldn't really be eating and drinking in your workshop anyway, but do as I say, not as I do......


I found ferric nitrate to be relatively inoffensive, but ferric chloride will stain everything and somehow seems to get everywhere! If you do spill either chemical, throw some bicarbonate of soda over it which will neutralise the acid content, then wipe with kitchen roll and put in the bin.


It's important that neither chemical is washed down the sink. As outlined above, for small spillages I cover with bicarb. If you use enough the powdery residue can be wiped away and put in your bin. In its liquid form, however, you need to put it in a lidded plastic container and take it to your local waste disposal site where it will be put with the batteries etc. An alternative is to let any liquid evaporate and wipe out the residue with kitchen roll, but in the middle of winter in England you might have to wait a long time!


My workshop is quite big and I didn't feel the need for extra ventilation, even when I was gently warming the solutions on the hotplate, but again, it's recommended.


It's important to remember to use only plastic or glass/Pyrex containers to hold ferric nitrate and ferric chloride - if you put them in metal containers they will eventually 'etch' their way out!


Designing


First of all you need to decide what you want to etch. This is the exciting part, but sometimes the hardest because once you start you will literally want to etch everything!


Unfortunately an in-depth tutorial of various software packages is beyond the scope of this tutorial, but I can give you the following tips:


It's important to consider which part of the image will etch and which will not. The toner acts as a resist against the acid, so when you print your image onto the blue paper, the black part will remain unetched and the remaining blue parts will etch.


For example, if you create a line drawing, you will need to decide if you want the background to be etched and the lines of the drawing to remain raised in relief (below right), or the background to remain raised and only the lines etched (below left). Usually I prefer the latter scenario. If so, you may have to use your computer software to 'invert' the colours of your drawing before printing.





It is best to create simple black and white drawings to begin with. It is possible to etch using photos converted into grayscale pictures, but the effect is more uncontrollable. When you're just starting out, no doubt you will want the immediate gratification of a nice clean etch like I did.


I like to leave a good margin around my images because when you come to transfer the toner to the metal, the parts around the edge don't always adhere very well.


Always remember that when you come to adhere the toner to the metal, the image will be in reverse, so please remember to print any lettering backwards!


I had to mess around in Inkscape and Photoshop to create the graphics for my bunny ring, but the examples on copper shown here were from Vector artwork bought from one of the many graphics platforms, but check out Etsy as there are lots of people selling graphics on there. You need them in a good resolution so you can resize them. I have used both jpegs and vector images. You can of course use free graphics available online but be aware that some of them rip-off work by other artists.



PnP Blue


You'll be glad to hear that you don't necessarily need PnP paper and a computer and printer to create a design. You can use lots of things as a resist - nail varnish, glue, permanent marker (e.g. Sharpie/Posca), tape, sticky-backed vinyl, stickers used in crafting, wax etc - but I find that printing a design gives me the ability to create images with much finer lines.




Art nouveau designs printed onto PnP blue etching paper
Design ideas printed onto PnP paper



I believe Press n Peel paper (above) was initially designed for printing and etching circuit boards; in fact my brother can remember doing this exact thing at school. It so often happens that industrial techniques can be used in art and this is one of those examples.


Vitrum Signum and a couple of other places sell it in the UK, but I've heard that you can also get a yellow type shipped from China. At this point I've never used it so I can't comment on it, but I believe it is cheaper.


The important thing is to print only on the matt side of the paper. You will no doubt want to test your design on normal white printer paper first to get the design in the orientation and size you require.



Art nouveau design ideas printed onto PnP blue paper
Design ideas printed and ready to use


Preparing the Metal


When you have your design printed in the size you want you can cut your metal to size (below). I have an old tabletop shear to do this for me, or you can simply cut out the piece with your saw.




A pair of compasses on top of a sheet of copper, ready to score and cut with a shear
Scoring metal ready to cut with a shear


I like to give my metal a fine 'tooth' before attaching the PnP which you can do with either sandpaper or wire wool (below). I then clean the metal with isopropol alcohol (or use your normal cleaning method) and avoid touching the surface thereafter as dirt and grease can stop the PnP adhering to the metal.




A piece of copper with an abraded surface
Cleaning copper and adding a 'tooth' to the surface



It's important to test the heat of your iron first with a piece of scrap metal and a scrap of PnP paper. I have mine set medium high, but I have no idea how that translates to the heat settings on any other iron. Place your metal on a ceramic or marble tile and put the PnP paper matt side down on the metal. Place your iron directly on the surface and apply a little pressure.


It can take several minutes to adhere properly, and you should see that the paper goes from being blue to becoming darker and allowing the image to show through. You can move your iron around if it's a large piece. If you notice that blisters start to appear and the plastic starts to melt then it is too high. It is a good idea to test the PnP to its limits and then adjust the heat of your iron to just under this setting.


I have set the heat on my iron so I can just place the iron over the paper and the metal on the tile and leave it for several minutes. While it is still hot I like to use a burnisher (I have an agate one but you can use the back of a teaspoon!) to burnish over the PnP paper a little. I use something small (like the head of an old nail) to hold the metal down with so I don't burn myself on the hot metal.


You must let the metal cool a little before removing the PnP paper or you will not get a good transfer. Even then be careful as you remove it. If you start to peel and find an area of the pattern that has not transferred, roll it back down onto the metal and apply more heat. You will likely find that the edges of your image don't transfer completely which is why it's a good idea to leave a decent margin around your image. Also, small items are tricky, but not impossible, to etch. I have etched a 6mm wide ring band so it can be done.



An art nouveau design transferred onto a piece of copper using heat.
The design transferred from the PnP paper to the copper surface.


For large or thick pieces of metal you may need to put the metal and PnP sandwich on a hotplate set at a low heat and iron on top of this. Be careful and check your work more often to avoid melting the PnP paper (below).




An iron on a hot plate with copper sandwiched between.
If you iron onto a large piece of copper you may also need to use a hotplate below the metal to get it to the correct temperature. Please excuse the state of my filthy hotplate!



Applying Other Resists


Despite your best efforts you will have sections of PnP that do not transfer, and you also need to protect the back and sides of the metal because any area not covered will be etched.


I use stick-on vinyl paper that you can buy from eBay or craft shops to cover the back. Cut to size and use a burnisher to try and get rid of any air pockets (you can use an old spoon to do this). Also make sure it is adhered properly around the edges so the etchant can't get underneath it.




Pink stick-on vinyl being smoothed by an agate burnisher.
Burnishing stick-on vinyl to the back of the copper piece to eliminate air bubbles.




I use any old nail varnish to cover the edges and any places that need touched up (I had to ask my mother for some as I'm probably the only woman on the planet who does not own a bottle of nail varnish!). You can use nail varnish on a tooth pick to touch up tiny holes in the transfer paper too. As I type I am being slowly gassed by the smell of peardrops (which I actually like), but it's probably not good for you so please make sure you have good ventilation!




A design transferred onto copper with nail varnish all around the edges.
What a mess! Nail varnish around the edge of a piece stops etchant getting under the vinyl and eroding the back. Blobs of varnish on the surface cover up any holes in the design that didn't transfer.



Leave the nail varnish until it is completely dry - I usually apply the resists one day and leave the nail varnish to dry overnight and then etch the next day.


Mixing the Acid


I bought the ferric chloride for etching copper pre-mixed, but I bought the ferric nitrate for etching silver in crystal form. I mixed the ferric nitrate up at a ratio of 300g ferric nitrate and 400ml de-ionised water and it worked well.


Please always add the acid to water and not water to acid. I think a good analogy is to think of acid as being like washing up liquid. If you have a bowl of water and add a squirt of washing up liquid to it, there isn't very much a of a reaction, which is good in the case of acids! If, however, you add the washing up liquid first and then add the water, the washing up liquid reacts and bubbles up, which is not good when we're talking about acids! That's how I remember it anyway.


As previously stated, please wear PPE, and in the case of ferric chloride, it stains everything! Bicarbonate of soda is your friend - I always keep a good stock of it and sprinkle it on any spills neutralise it.


If you're going to etch large pieces of copper you ideally want to store your ferric chloride in a shallow container with a lid. It must be plastic or glass and not metal. I found a Pyrex oven dish with a plastic lid which is great for this task. I only etch small pieces of silver (because of the cost of silver), so I store the ferric nitrate in a lidded jam jar.


Etching


Your pieces need to be suspended in the acid upside down so the metal can fall cleanly away from the face of the piece as it etches. It's as easy as sticking a loop of cotton to the back of your piece with Sellotape and hanging them from chopsticks or a dowel suspended over the acid receptacle (below). In the case of the jam jar I use a toothpick to suspend them. I always find it amazing that these two acids will etch metal, but they won't touch the cotton thread I use to hang my pieces from.




Copper attached to the back of a piece of copper coated in pink vinyl.
Using cotton and Sellotape to create a loop to suspend the copper in the acid.



Another technique involves sticking a square of polystyrene to the back of the metal with double-sided sticky tape and floating it on the acid bath. This is the 'float boat' method.


The amount of time your piece needs to be in the acid depends on several things, namely the temperature of the acid and it's strength, which is why I'm not giving out any accurate timings regarding how long your piece needs to be in the bath for. The strength of the etchant declines over time and at some point you will need to replace it. You can speed up the etching process, however, by applying a little heat.




Pieces of copper suspended from cotton in a bath of brown ferric chloride on a hot plate.
This is the fun part! Pieces of copper suspended from cotton in a bath of ferric chloride on a hot plate.



Personally I use a hotplate in my shed to warm the acid a little (above). It only has to be warm and certainly not boiling! I once left a silver ring band in some acid on a hot plate and by the time I remembered, not only was the acid at a nice simmer, but the band had almost completely disintegrated! It's an expensive and slightly dangerous way to learn!


A safer way (if you're forgetful like me) is to use a bain marie (or a timer!). Put a small bowl containing the acid inside another larger bowl and pour warm water into the large bowl. This will heat the acid safely. You can replace the warm water two or three times during the etch.


The resists you apply will not stand up to acid forever. Ideally it's nice to get a decent etch within an hour to an hour and a half before the nail varnish etch starts to degrade. Also consider how deep you need the etch to be. When I am applying opaque enamel into etched recesses I like to be able to get 3 or 4 thin coats in there as the first one often discolours.


It's best to check the etch every 15 minutes or so. You can do this by eye by pulling the piece out of the acid bath and eyeballing it.


Cleaning


When the etch is done use plastic tweezers to remove the piece. I use a plastic takeaway tray with straight bicarb in it to initially remove the acid from the piece. I also have a couple of water baths mixed with bicarb to wash my tools in. I wash them in the first one and let them soak in the second one. Again, this waste water should not be be washed down the sink, but collected and taken to a waste disposal site.

You can wash off the excess bicarb and acid off the etched piece in the water baths too. Then I have another takeaway tray with some acetone (nail varnish remover) in. I usually leave my pieces in it overnight just to dissolve the gloopy varnish. There will be nail varnish residue and toner still on your pieces and they look pretty awful at this stage. Use kitchen roll to wipe of excess liquid and then scrub the pieces under a running tap to remove any residual gunk.




Etched copper pieces that seriously need a good clean!
Recently etched and cleaned coper pieces. Still pretty gunky right?



Finally, you can use whatever method you prefer to sand your pieces (below) and reveal the etch in all its glory for the first time! I use my Dremel rotary flex shaft which makes my life a lot easier.




Bright shiny copper pieces with etched art nouveau designs.
The final reveal! It's very satisfying when you have a good etch and that beautiful peachy copper colour finally appears after sanding.


Enamelling


Although this post is more about etching than enamelling, I thought I would show you the results of a couple of etched pieces, including one after enamelling.


Remember when I said I had etched a 6mm wide ring band? The photo below left shows the band after the image of two running hares had been transferred. I had to do a bit of touching up with nail varnish to seal the sides after I put stick-on vinyl on the back.


The etch was a great success and you can see the finished sterling silver wedding band below right.







Below you can see an example of opaque enamel being added to a piece of etched copper. I find that the enamel doesn't really show its true colours until the third or fourth layer, so it's important to get a relatively deep etch. However, this was done on 0.8mm thick copper so when I say a 'deep' etch it's all relative!


The middle photo shows unfired enamel, while the photo below right shows the enamel after firing. You can see hairline cracks in the lower part of the enamel because the copper wasn't really thick enough and as the metal has moved, so has the enamel.







I really hope you've enjoyed this little tutorial and that you might try out etching sometime. I've got a feeling you might become addicted!



Kelly x


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