UPDATE: There's some great information on this page and it's comments, but I've recently published a far more comprehensive article here: Etching Tins with Salt Water and Electricity
With this project I wanted to try a number of new things:
- Magazine pages as cheap toner transfer media
- Copper electroplating
- Etching Altoid tins with a salt water solution
The copper plating met with mixed success, but the other two methods resulted in some nice pieces.
Note: blue vitriol and muriatic acid are archaic names for copper sulfate and hydrochloric acid.
Magazine pages for toner transfer:
While looking for information on transferring toner using a fuser assembly from an old laser printer I ran across several websites where people suggested using glossy magazine pages for transferring printed circuit board images to a copper substrate. I thought I'd give this a try for etching Altoid tins, so I cut up a likely magazine.
Preparing the Altoids tins turned out to be harder then I predicted. The paint stripper I use comes in a spray can and is sold as "Paint & Epoxy Remover." It's strong stuff. If you get even a drop on your skin it hurts like hell and you need to flush the area with lots of water to make it stop. Most paints just wrinkle up and fall off when I hit them with this stuff yet the paint on the Altoid tins required several minutes of scrubbing with steel wool while wearing nitrile gloves (latex gloves fall to pieces in seconds.)
- Print the image on a magazine page
- Rough up the surface of the Altoids lid with Scotchbright
- Clean the lid thoroughly with alcohol
- Iron the image onto the lid
I cut a block of wood the size of the base to support the lid while I pressed down with the iron.
This is the Lady Ada Lovelace, a contemporary of Charles Babbage and a woman oft sited as the first computer programmer, she having written a series of notes comprising an instruction set for calculating Bernoulli numbers on Babbage's Analytical Engine. You don't get more Steampunk then that!
Once the transfer is ironed onto the tin you soak it in water and then carefully peel off the paper, layer by layer, leaving just the toner behind. To get the last of the paper off just gently rub with your thumbs.
I used the cut-out in the magazine page as a template for cutting a mask from packing tape, I wanted to only copper plate part of this tin's lid.
So far all of the toner transfer methods I've tried; Laser printing on Inkjet paper, Press-n-peel blue, and magazine pages, have worked just fine. Press-n-peel is probably the easiest to peel off, but the hardest to iron on if there are large solid areas of toner.
Copper Plating Altoids Tins:
For my first attempt at copper plating I simply connected the lid to the negative side of a 1.5 volt power supply and dipped into the blue vitriol (copper sulfate) solution that I have been using for my brass etching experiments. I used a length of copper tubing for my anode.
From the picture below, this appears to work. Alas, what you see is just a coating of copper powder, nothing has actually stuck to the tin plate on the Altoids tin.
I speculated that perhaps my solution was contaminated so I did a little research (see Technical Links) and tried a solution with a different composition. I filled a container with about a gallon of water and added a table spoon of Muriatic acid (25% HCl) and a pinch of salt. Since you can't plate copper out of the solution until there is copper in the solution I inserted a dummy cathode and run the cell with the 1.5 volt power supply for about 6 hours.
After this time the solution had a faint blue tinge and I replaced the dummy cathode with the tin. Unfortunately, results were identical to the earlier attempt.
For my next attempt I connected the metallic barrel of a painters brush to the positive side of my power supply and the negative side to the Altoid tin. I dipped the brush in the blue vitriol solution and "painted" it on the tin.I actually had some success with this.
However, the most successful technique turns out to be the simplest, simple apply a solution of blue vitriol with a cotton swab using a circular motion. Q.E.D.
You can vary the qualities of the surface by using different strokes to lay down the copper and you can polish the resulting plate on a buffing wheel with a touch of rouge.
Salt water etching Altoids Tins:
The next thing I wanted to try was etching the Altoids tins. I printed and applied a Press-N-Peel blue mask to one of the tins and attached it to the positive side of a car battery. A piece of copper pipe was attached to the negative side and both electrode and work piece were immersed in a gallon of water that had approximately 2 cups of salt dissolved in it.
The salt water started to bubble furiously and a dark murky green-brown precipitate began to form.
Foom! "Ah! the bubbles are indeed hydrogen."
After about 7 minutes I took the Altoid tin lid out, rinsed it and used paint stripper to remove the toner mask.Seven minutes was probably just a bit too long as you can see by the perforations in the upper right.
I then coated it with the blue vitriol (copper sulfate) solution using the cotton swab method and polished it with a buffing wheel and a bit of rouge.
In all I made half a dozen tins using slightly different methods. Some of the early plating experiments actually turned out to be quite pretty once I sealed the powdery copper layer with a coat of lacquer.
The finished results:
This one is a straight salt water etch with a bit of black paint to bring up the details and a finish lacquer coat.
This is a salt etch with a layer of copper applied using the cotton swab method and blue vitriol solution. It was then polished with a buffing wheel and a bit of rouge.
My first plating attempt was a failure but looked so interesting I put several coats of lacquer on it to fix the powdery copper bits in place.
This Altoid tin was masked with an oval piece of packing tape and then lightly etched. Next the mask was removed and a positive toner image was ironed on. Finally the tin was plated in copper using the cotton swab method and the whole thing lacquered.
The tin below is the big success of the batch. It was a straight salt etch and had the blue vitriol solution carefully applied to certain areas with a cotton swab. The etched area was cleaned up a bit with some 400 grit paper and the piece was lacquer sealed.
The Lady Ada Lovelace