Etching

Now that the toner is on the copper, we can etch it.
This means that you have to have made the tank, and found a suitable power supply.

The power supply needs to be at least three volts, and absolutely has to be DC, or direct current. According to my friend, who is doing second year engineering at the ANU, you need three volts for the copper to start coming off the plate. Much more than three volts is overkill, but it does no harm. However, the higher the voltage, the more leeway you have (theoretically) with the size of the plates and the distance between them, as well as the concentration of the electrolyte solution. If you measure the voltage across the two plates while they are etching, it reads higher the further apart they are. This is because of Ohm's law, which states that Voltage=CurrentXResistance, or V=IR. If you move the plates close to each other, the resistance between them drops, causing the voltage to go up. The same goes if you put more copper sulphate into solution.

The procedure for etching is this: Figure out some way of suspending the plate as close to parallel as possible with the cathode. I drilled two holes, one near each of the top two corners. Then I put some fencing tie-wire through the holes and hung it from a bit of aluminium stock so that it would hang below the water line.


Connect the positive of the power supply to your piece, and the negative to the plate in the tank, and turn the juice on.












Every fifteen minutes or so, turn the power off and scrape the crap that forms on your piece off with a toothbrush. Return it to the tank and continue.















This particular piece only took about half an hour to etch, but that's because it's so small. The bigger it is, the longer it takes. This is because the current will spread out pretty evenly over the surface of the copper. Because there is only so much current, if you have a large plate, there will be fewer amps per square centimetre. I once etched a card box with a picture about 5X7 cm, which took about two hours.






Here's the badge that I etched, based on the picture in the second post. The lines were about 0.5mm deep, and very clean. The only problems with the etching quality are the parts where I failed to transfer the toner properly, i.e the wing tips, and three parts of the zeppelin. The other flaw is that there is some pitting on the wings, but I suspect that that is due to the large spaces of black. It might work better if that part of the picture were made up of lines.











If that is where you're going to leave it, then now is the time to ink it. This can be tricky if you don't have the right stuff, but it's not all that bad. If you're going to do something else, you shouldn't ink it yet.

Interesting fact: I touched the back of the plate before etching, and was left with an etched fingerprint on the back. The back does etch, but not deeply.

Toner transfer

This is a technique that I used to use to manufacture PCBs (Printed Circuit Boards), but I realised when I read this that it could be used for other things too. The basic concept is this: A laser printer melts stuff called toner onto the page, if you're careful, you can then re-melt the toner, onto something else! The wonderful thing about toner, is that it's both acid resistant, and electrically non-conductive. This allows you to use it for a mask on either electro etching or acid etching. If you want to create your own one-of-a-kind, hand drawn plate, you can use a soft ground, which is a thick oil based ink (the one I've got is at least). You paint it on, wait a couple of days for it to dry, then just scratch your picture on. But I'm using the toner transfer method.

Here's what you need:
As pictured, you need an ironing board, with a cloth on it so I don't burn the cover, a sheet of copper, which I'm using for practice, a nibbling tool, steel wool, isopropyl alcohol, scotchbrite, an iron and a block of wood.

Print your image onto a page from a glossy magazine (I used New Scientist), make sure the image that you are etching is printed in black and white (the colours on the magaine page don't matter at all) , and the exact opposite of the picture you want to have at the end. Ergo, the colours (all two of them) are inverted, and the picture is mirrored.

Cut out your image, and a piece of copper that the image will fit on. That's what the nibbling tool's for, but you can use anything that works. Now you have to clean it REALLY well. Scrub it with isopropyl and steel wool until it gleams, you can use the scotchbrite instead of the steel wool if you want. Make sure there is no dust, dirt or oil on the surface, that includes fingerprints.

Once it's clean, wrap your image around it, with the picture over the cleaned surface, and the edges of the paper behind it. Now iron it. Put the iron on its highest setting, dry of course, and press hard, moving the iron around a little. It sometimes helps to rub it with a roller or the back of a spoon or something. This can take around 2 minutes, but practice will tell you exactly how long. Because ironing boards are padded, I always put a block of wood under the copper, but if you're ironing on your workbench, there's probably no need. But it might still help.

Once the ironing is done, put the copper and paper in some hot or warm water. Let it soak for about 10 minutes, then gently peel the top layer of paper off. Soak it again, and take more paper off. Continue this until there's almost no paper left, then you can rub the rest of the paper off. You want tho be left with a piece of copper with only toner and empty space on it. Nothing else. And that's the toner transfer method.

You should be left with something like this:


My technique wasn't great on this one. Decent, but not fantastic. I missed the wing tips and the bottom tooth of the gear, and I think that I accidentally ironed some of the blue from the magazine page onto the copper too. If you have an etch resist pen, sold in electronics stores, you can go through and touch up bits that are missing, and you can carefully scrath lines out of the toner when bits that shouldn't be there are there. (By the way, don't be fooled by the shaky lines, they're actually very sharp, my camera's not great is all.)

Aims and materials.

When I'm done with this particular set of experiments, I want to be able to get good quality etches, with nice straight lines, I want to be able to 'etch machine' as well, which is where you etch right through the plate, causing a bit to come off. I want to minimise surface pitting, and master toner transfer, which I'll explain at some point.



The project I'm going to be making for this is a badge, the image I'm using for the badge comes from a web comic called Girl Genius that is quite amusing, and it's an airship pilot's badge. I think it's quite a striking image.




The materials I'll use are:
Large Tupperware container
Copper Sulphate
Plates of brass and copper (Obtained from A&E Metal suppliers )
Variable power supply
Laser printer New Scientist magazine
An iron and ironing board
A Roller
Isopropyl alcohol
Black paint
Steel wool
Scotchbrite
Brass brooch findings, also from A&E



You might also find one of these useful at a later date.














The first couple of steps I have had completed for a while now. They're as follows: Make an etching tank. I had some old float valves, enormous ones, and the float on one of them was bashed in and useless. Or so I thought when I got it. It was made of copper, so I cut a bit out of it for my cathode. I drilled a couple of holes in the side of the Tupperware container and in the copper scrap, then bolted the copper to the inside of the tank. That's the cathode done.

The next step is the electrolyte (the salt solution). I went to the hardware store and got some copper sulphate, a blue crystal used for killing plants, or you could 'acquire' some from the school's chemistry dept. Dissolve some of the copper sulphate in water in the tank. Obviously, you want to keep the water level below the holes in the sides of the tank. If you're not going to use it straight away, put the lid back on and put it out of the reach of lurkers (A.K.A fiendish sisters)

Lurker #1

Galvanic Etching

I have been interested in making etchings in brass and copper for some time, and in fact made a card box out of copper, with a scene from Alice's Adventures in Wonderland Galvanically etched into the front. Once I had finished that, I lent my etching tank to a good friend of mine, and I only recently got it back. But now that it's back on my workbench, I am going to improve the quality of my existing etching skills, and broaden my repotoire of techniques. I'm going to start with a brief history of Galvanic etching first though. The benefit of the ability to etch images and words into various metals was twofold. They were used in printing, where the plates would be of the Intaglio variety, where the raised part of the image were the lines desired on the final piece, a negative of the final image if you like. As well as this, etched plates can be quite aesthetically appealing. Galvanic etching, also known as electrolytic, or electro etching, is a process that has been known since the 19th century, the original description of the process having been published in 1855 under the name electro-etching. Prior the widspread use of electrolytic etching, acids had been used in their place, these acids included nitric acid, hydrocloric acid, or ferric chloride. None of which are particularly pleasant chemicals (http://www.greenart.info/galvetch/advan.htm). The basic theory of Galvanic etching is this: If you suspend two plates of metal (both based on the same metal, that is, if you have a copper plate, you can couple it with brass, copper, or bronze) parrallel to each other in a solution of the same metal (in a salt form usually), and pass an electric current from one to the other, particles of one plate will become dissolved in the solution, and will then be dposited on the other plate. Electro-etching is essentially the polar opposite of electroplating.

In this diagram, sorry for its low quality by the way, the brass plate is on the left, and the copper is on the right. The plate connected to the negative supply is always the cathode, or K, and the positive is always the anode, or A. When you etch, your piece is always the anode, and a bit of appropriate scrap is the cathode. Reverse this for plating.