Wednesday, 17 July 2013

Acid Etching … musings and plans – Part 1

I have done acid etching of PCB for electronics, and it isn’t very hard. To take things up a notch, I want to do some acid etching of some brass plate. This is all leading to part of my current down-scale projects.

The idea is very simple … make a design using Photoshop (or another image processing tool). The image is the same size as the piece of brass that I am working with (35 x 5 cm). I want the design to be simply a border with cogs in it (steam-punky) and with a bit of text in one of the cogs.

OK, so I did that bit. I got a good steam-punk texture from the Internet and played with it until I was happy with it as a pattern. I made a pattern filled border that was also a simple repeated design and made sure that the bits that I wanted to be etched were white and the bits that I wanted to remain were black (or shades in between).

I printed out the design onto my black and white laser printer and then ironed the design on to the brass plate.

Sounds simple? It is … except that I stuffed up in two ways:

  1. I forgot to reverse the image;
  2. Photoshop trashed the image when I saved it (old version … long story).

Still, I got the image transferred on to the brass plate.


The iron was on it’s hottest setting and I kept the iron moving on the paper for about 5 minutes.


You can see that the transfer isn’t perfect, but I thin that this will add a patina to the etch when I’m done.


The next step will be to paint around the transfer so that none of the border will be exposed when I start rubbing acid onto it. I’m going to use an acrylic paint to mask the edges of the brass plate.

After the plate is properly masked, I will move on to the acid etching part of the process.

As a heads-up … the ingredients that I will be using for doing the acid etching are:

  • hydrochloric acid;
  • hydrogen peroxide;
  • heavy duty rubber gloves;
  • acid safe plastic container (for the acid);
  • cotton wool swabs;
  • nail polish remover.

The hydrochloric acid/hydrogen peroxide mixture has already been converted into cupric acid (by adding copper) and there are plenty of good resources for making cupric acid on the interweb.

I will be putting the acid into the container and then wetting the cotton wool swab with the acid and gently rubbing the surface of the brass plate with the acid. This should have the effect of etching the parts of the design that are not covered with the resist (paint and laser printer ink). After that, the plate is bathed in water to neutralize any acid that is still on the plate, then the plate is cleaned off with the nail polish remover. That will remove the laser printer ink and help to clean off the acrylic paint.

What I should end up with is a nicely etched brass plate.

I am practicing this now so that when I come to make the pieces for the goggles, I can pre-etch them. It would be a lot harder to etch the pieces when they are shaped … so I’m going to do that first.

Later, I will make a very simple prototype pair of goggles (with no lens and no moving parts) so that I can get the basic design bedded down.

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