Monday, 22 July 2013

Acid Etching … musings and plans – Part 2

Quickly … to the redesign!

After last parts failure to save my design, I have quickly made up a new, smaller design. This one is a simple 5x5cm design as a proof of concept.


Negative and flipped horizontally … I also added the word “Asylum” across the gargoyles brow.

This was then printed out and ironed on to the brass plate.


Now it is reversed through the magic of transfer printing.

I then used a white acrylic paint to block out the edges of the plate and the right-hand edge so that the acid wouldn’t eat away at the rest of the stock. I also painted some white paint onto the back of the stock so that the acid wouldn’t mark the back of the piece.


I had to make a swab for the acid. This is simply two bamboo skewers wrapped together with a rubber band and with a cotton ball at one end.


Next, I poured my acid into an acid proof container and then swabbed the acid onto the design using my home-made swab.

When I thought that I had rubbed enough acid into the design, it was time to clean the resist off the stock so that I could reveal my masterpiece …


Well … not so much masterpiece as, very, very faint etching indeed.


I think that I did two things wrong here:

  1. The acid was not fresh … it had been sitting in the bottle for about two months. The acid needs to be refreshed from time to time (add more peroxide, add more hydrochloric acid). I noticed this previously when I was etching printed circuit boards; and
  2. I certainly didn’t swab acid onto the design long enough.

No great loss, I have learned my lessons and I can move on. I will get some more peroxide so that I can freshen the acid, print and transfer again, and revisit this design at a later date.

Importantly I learned that, essentially, my plans are feasible with stronger acid. I won’t make those mistakes again and I did not ruin the stock. In a worst case scenario, I could polish the design out of the brass stock (if I really needed to).

I found some other gothic designs that I like and will probably use in the goggle design. I’m going to be going for a steam-punk/Cthulhu inspired design when I finally do get on to that project. Probably working in something like this …

chthulu octopus

I’ve seen this in a couple of places … including tattooed onto someone's back. Either that or draw my own Cthuluesque design.

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.

Monday, 15 July 2013

Now that I’m moved

Now that I have moved to my new abode (temporary accommodation). I don’t have a lot of space to do much … so I have to scale my experiments and prototyping to stuff that I can do in a small room and on a desk. Not a lot of scale really.

So, over the next couple of weeks, I’ll be doing some small scale prototyping of moving parts that I will be working up into a pair of steam-punk style goggles.

The basic design of the goggles will be a simple affair with two ocular apertures, ideally with some slotted eye-piece covers and a working mechanical iris.

The prototype goggles will be all about the “how to” and won’t necessarily involve a whole working model at the end of it.

I am going to start by making a single eye piece and see what I can make to “gussy” it up.

I also want to use the prototype as a workbench for acid engraving. I have some cupric acid that I have produced from doing some electronic PCB engraving, and I want to see how far I can go with this technique for an artistic design on brass-work. Later, I might even do some Dremmel pierced work on the frame as another piece of experimentation.

So … on to the plan.

I have bought a couple of brass rod and brass cylinders (including some nifty hollow hexagonal pieces). I want to use the brass rod and tube to make some brass nuts for the goggles. This should be fairly straight forward. Cut the rod, cut the tube, flux the rod, and braze. When the rod and tube are in one piece, use a tap and die to cut the thread on the nut and the goggle body where the nut will attach.

If you are interested in seeing some awesome steam-punk goggles … do a search for gogglerman, his stuff is truly inspiring.

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