I was looking a while for a good set of instructions for electric copper etching and found a quite good instruction at Jake von Slatts Steampunkworkshop and decided to refine it a bit and create an own instruction set in german. Now translating it back, i will also provide it here, making it my first instructable...

Here is an overview on what will be neccessary during all the steps:

- a power source ( DC, continuous current ) and electrodes

- an electrolyt ( a conductive liquid ): copper sulphate

- copper as basis material and for the anode

- some plastic or glas containers.

- inkjet paper

- sanding paper

Step 1: The Method

The whole process i will describe is based on an electrolytic bath using a copper sulphate dilution.

Electrolysis itself is a quite easy thing: it is a process, which enforces a chemical reaction due to electricity. What kind of reaction is happening depends on the ingredients being used.

A detailed description of electrolysis can be found here

What do i need for the setup?

- a power source ( DC, continuous current ) and electrodes

- an electrolyt ( a conductive liquid )

- copper as basis material and for th anode )

- some plastic or glas containers.

The Power Source

It is a good idea to have a switchable power supply. I use one from Graupner.

It can adjust both current and voltage, so i can vary a bit depending on what materials i use.

I would aim at having at least 12V and 15-20A output.

The electrolyt

A traditional substance for eletric etching of copper and zinc seems to be copper sulfate.

It easily dissolves in water to a nice blue liquid. I used a concentration of 4 parts water to 1 part copper sulfate ( assuming 1 kilo being one litre ;) ). Copper sulfate is defined as an irritant, but can be bought online. The potential danger is that it destroys organisms over a longer period of contact. Don't put it on your skin and do not drain it in the sink.

If you need to get rid of it, contact your local waste disposal dealer.

Copper

Since you want to etch copper, you need to copper object you want to etch. This will be attached to the anode of the power source to let the current run through it. On the cathode you need another piece of copper, on which the Cu2+ molecules can settle. I actually used brass, also works fine, as will all other materials, that are able to join with copper.

Written in chemical terms, this happens:

On the Anode: Cu => Cu2+ + 2e-

On the Cathode: Cu2+ + 2e- => Cu

The anode dissolves slowly, producing cations, which will transform copper at the cathode through reduction of copperions.

Step 2: Image Transfer

There are two useful methods of transfering the desired image to the copper plate: Photo exposure or direct toner transfer, which saw as the easier ( but maybe more inaccurate ) method i will describe now.

Before continuing, we have to clean the surface of our copper thoroughly, using rubbing alcohol or other good cleaner. No spot of whatever may be left before the transfer.

Now we need a negative of the image we want to etch. You need to print that on a as glossy as possible sheet of paper. You have to experiment a bit. I chose photo paper for inkjet printers, but i read, that also pages from product catalogs are good. You need a paper, which has a very flat surface so the toner cannot stick to it too good.

Use your iron at a high temperature to first heat up the copper. Then put the sheet with the print towards the copper on the plate and apply it with high pressure of the iron. Take care not to move the sheet or the picture will be messed up. How long you have to press them together depends on the materials used. Again. a bit experimenting is neccessary.

When the sheet is stuck on the plate, put i in hot water for some minutes, until the paper just comes off. After a bit of soft rubbing, the paper should come of completely and only the toner remains.

That was the tricky part...

Step 3: Etching

In this step, you will do the etching ( and waiting... )

You will do the setup described in step 1. The copper plate, that you want to etch has to be attached to the anode using some conductive connector. I used alligator clips, but you can as well just build a small conductive frame, which holds the material. Again some experimenting is needed... Same for the cathode.

The coppler plate has to be covered in the dilution as complete as possible. parts, that are not covered, will not be etched.

When everything is setup properly, power on the power source. I used 15V and 20A as an initial value. If you measure the resistance or the current flow, it will change with time and more power will flow.

Take care, the dilution does not get to hot. Some steam is fine, as long as it is colorless and does not smell. Boiling water will destroy the plate very likely.

From time to time slew the anode plate a bit, that the coat, which will appear after a while, disappears. Try not to remove the toner.

The duration of the process depends on how deep you want to etch and how much current your power source is able to deliver.

The piece i took for demonstration took me almost an hour.

Step 4: Finishing

Let the dilution drip of well after the etching. Let as much as possible drip back to the container, since you do not want to put it in the sink. Then clean it with clear water. A low concentration of coppersulfate won't harm the environment, but keep it as low as possible.

Use some very fine sanding paper or grinding swart to clean the plate from toner remainders and to get a nice and clean surface.

As you can see on the gun handle, i did not do the transfer properly. There was not enough toner on that line, or it was not well transfered, since it seemed to have fallen off during the etching.

Well.. that' it.. etching done...