Thanks for all your comments. I enjoyed making these and am thinking about other applications – some good suggestions there, Dennis.
Judy – I’m not sure how hard etching is. If the process I did is all there is to it then it’s not hard at all!! There are quite a few variations to the method of etching - some being more complex than others.
Wendy – I used a brass brush with washing up liquid and water to remove the Sharpie though a scourer would also work. I’ve outlined what I did below.
6v lantern battery
2x 500mm lengths of 0.4g copper wire – doubled
2x small foldback/bulldog clips
10 x large (70mm long) paperclips, 1 annealed
Empty, clean coffee jar
Black Sharpie Permanent Marker
Washing up liquid
0.3g copper sheet
Green washing up scourer
Straightened the annealed paperclip and used it to wrap around the other 9 to make a bundle. I left the bend on the larger end so this can be hooked onto the inside of the coffee jar. This is the cathode.
Filled the jar with enough water to sufficiently cover the piece of copper when placed upright. Added enough salt to the water so no more could be dissolved (I did this in stages rather than dumping a large amount in). This is the electrolyte.
Wrapped one end of the doubled copper wire around the ‘handle’ of one clip.; connected the other end to the positive (+) terminal on the battery. Do the same with the other wire and clip and attach to the negative (-) terminal. I just wrapped the wire around the springs a few times. Be sure not to allow the wires to touch each other as it could short the battery.
1. Cut copper sheet to correct size on 3 sides and left about 6mm - 10mm extra ‘waste’ copper on the remaining side. This is the anode.
2. Washed and scrubbed copper clean with washing up liquid and scourer until water sheeted of it to ensure a clean surface. I did this to both sides of the sheet - if I messed up one side when drawing I could just flip it over. I handled the copper by the edges to dry it and from then on only with gloves on. Oil/dirt/snot can prevent the marker pen from adhering properly.
3. Drew on design including a border around the image and let dry.
4. Taped up the back of the piece. I didn’t tape the sides as the metal was so thin.
5. Clipped the positive end to the ‘waste’ bit of copper on the piece and lowered into the electrolyte. Positioned the piece so that the clip was above the water line but the design (and some ‘waste’ copper) was submerged. I used a blob of blutack to fix the wire in place on the edge of the jar.
6. Hooked the paperclips on the inside of the jar opposite the copper. Clipped the negative end to the paperclip hook.
7. I left each piece to etch for about 40 minutes to an hour. I checked the depth of the etch after about 20 minutes.
8. Removed tape, scrubbed off marker pen using brass brush and washing up liquid under running water.
Metal attached to the positive (+) end will be etched
Metal attached to the negative (-) end will produce bubbles
The only item I purchased specifically was the battery and am quite pleased with how the etching turned out using these basic items.
Fine detail drawn on with the marker did start to come off mid etching. This could have been due to removing the piece when checking the etch depth but I had to do this as the electrolyte was too murky to see through. I patted the copper dry with a paper towel and applied the Sharpie again carefully. As the metal had been etched, it was easy to reapply using side of the pen nib.
After a few etchings, I strained the electrolyte through a paper towel and reused it.
I would most likely use a different resist if I wanted a deep etch on thicker metal.
If the metal was thicker I would have used tape on the front of the piece to create the border and folded it around the sides sticking the tape to the back to ensure the sides did not get etched away.
I ironed one of the designs (non steam iron, highest setting, placed copper in between a folded paper towel) to see if this would fix it further - I can’t be sure with my limited experiments to see if it made a difference.
Sorry for the lengthy post but I hope it helps - please feel free to ask any questions. I shall post an image of my set up as soon as I get a chance.
Google searches “saltwater etching” and “electro etching” or combinations of the two bring up some interesting pages, how-to’s and other experiments. There are also many different resists some giving quite accurate results (from what I’ve read not personal experience).