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This is my first step-by-step instructable, so please provide feedback. I know some of the pictures are fuzzy and I have no idea why...

There are many instructables on etching, but I thought I would add one for etching aluminum. I was commissioned to make an etched aluminum rune pendant, so I though this would be a simple one to document...

You will need:

Aluminum stock

Some way to cut the aluminum

Paint

Something to scratch paint off

Salt

Water

Copper Sulfate

a small bowl

a drill

creativity

Step 1: Cut and Shape Your Aluminum

I use a bandsaw for most of my cuts, but you can use what ever tools you have at hand. Hacksaw, dremel, jigsaw, snips or shears...

Cut your aluminum stock to the finished size. Use sanders or files to smooth the edges and round the corners.

When it is shaped and smooth, give the aluminum a quick clean with a wire wheel or brush...

Step 2: Apply a Paint Mask

Next, paint the entire piece of aluminum. I use automotive primer because it dries quickly. You can use any paint: oil, latex, spray, brushed, even paint pens. Be sure to cover the entire piece, both sides and all edges. The etching process will find any holes in the paint.

Be sure to follow the paint instructions for recoating. This step can take anywhere from an hour to several days depending on what you use.

Step 3: Scribe Your Design

Once the painted mask is dry, you can scribe your design. I use a home made steel point, but you could use a knife, xacto set, toothpick, or anything that can scratch away the paint. Use your point to remove the paint from the areas you want etched away. Be sure to fully expose the metal. If you remove paint from an area you want covered, use a paint pen to touch up your design. When you are finished, gently wipe away any loose paint and give your design another look-over...

Step 4: Electrolytic Etching

Now we etch...

Mix equal parts copper sulfate crystals and table salt into water. I mix about a 1/2 cup of each into a 1/2 gallon of water. I also use a bottle with a cap so I can shake it to mix. This mixture is fairly safe, but please wear the proper protective equipment when using any chemicals. Do not mix more than 1/2 gallon of solution.

The etching solution will be blueish-green when mixed. The etching process is driven by the ration of copper ions to aluminum, so the more solution you have in the etching tank, the faster the aluminum will etch. I use recycled plastic dishes for etching. Fill your etching tank with solution and drop your painted aluminum in. Etch time will depend on the aluminum, the etching solution concentration, volume, temperature, and many other minor variables. Monitor the etching until you have an idea how it is going. A dark flluffy copper cloud will form over the exposed aluminum areas. I use a small brush to to stir this away. The solution with etch the aluminum as long as there is opper in the solution. If you see the etching solution turning to a clear color, add more copper sulfate and re-mix the solution

Keep watching the piece until the etch is as deep as you want. When finished, pull it out and wash it off with soap under under running water. This should wash away any solution and stop the etching process.The pendants in my pictures etched for 8-10 hours.

The etching solution can be stored for reuse or washed down the sink with plenty of cold water. If pouring down the sink, let the water fun for 5 minutes after you pour it.

Step 5: Remove the Mask

Use whatever method you want to remove the paint. I use a wire wheel on my bench grinder, but you could also sand it off or use a solvent. No matter what you use, be sure to remove all of the paint.

Step 6: Finishing

Now you get to add all of the finishing touches.

First, drill the hole for your cord or bail. use a larger bit or a file to remove any burrs around the hole.

Next you can:

use files or sandpaper to distress or "age" your pendant

OR

polish with compound for a high gloss

OR

use a wire wheel for a modern brushed look

OR

do what you want how you want!

I use a commercial product to darken aluminum. It is called "aluminum black" and can be found online.

When finished with the finish, add a jumpring or string it through the drilled hole, wear, and enjoy!

<p>Um...if this is electrolytic etching, where are the instructions regarding the electricity? How much current, how long, what kind of power supply?</p><p>And, why the copper sulphate; what does it do?</p>
The solution provides the 'current' for etching... it is not an acid etch, but an ion exchange, therefore an electrolytic etch.
<p>Ahhh, the light goes on! Thank you, good sir! </p>
<p>Try doing a Lord of the Rings one with dwarf runes on it!</p>
<p>Wow! That is cool. I think I will do this to some of my cast aluminum ingots.</p>
Very nice job on the instructions and a great help for a few projects I want to make! Thanks!
<p>very cool. nice use of common materials to get the job done. </p>
<p>I understand the concern over the copper sulfate going down the drain... but the copper sulfate I use is made to be poured down the drain. It kills roots that work into a septic system. If you are on public sewer, then the WWTP can handle 1/2 gallon of copper/aluminum sulfate. If </p><p>If you are not absolutely certain that your waste water is completely <br>isolated from groundwater, and does not discharge into a waterway (even a <br> ditch), then you shouldn't be flushing your toilet or running your sink!</p><p>Even with a low flow faucet (say 2gpm), if you flush the water for the suggested 5 minutes, you just ran 10 gallons after 1/2 gallon of mixture, which is plenty to flush the drianline out of the house.</p>
<p>Ooh, so cool! I totally want to do this. :)</p>
<p>Well done. The only change I'd recommend is that I'm pretty sure your solution would be considered household hazardous waste and should be taken to a collection center.</p>
<p>They look really nice, and I will probably follow this instructable at some point, but I have a couple of points:</p><p>&gt; Aluminium will react with copper sulphate normally - what is the benefit of adding salt?</p><p>&gt; Just pouring the copper sulphate down the drain can be a <em><strong>really bad idea</strong></em>. It is corrosive and an environmental toxin when mishandled (it is used as a herbicide, fungicide and pesticide). If you are not absolutely certain that your waste water is completely isolated from groundwater, and does not discharge into a waterway (even a ditch), then you must find alternative means of disposal.</p><p>&gt; Aluminium sulphate (formed during the etching reaction) is also corrosive and acidic, and reacts with the water to form sulphuric acid.</p><p>Under UK law, both substances must be disposed of as Hazardous Waste.</p><p>See:</p><p><a href="http://www.jmloveridge.com/cosh/Copper%20Sulphate.pdf" rel="nofollow">http://www.jmloveridge.com/cosh/Copper%20Sulphate....</a></p><p><a href="http://www.jmloveridge.com/cosh/Aluminium%20Sulphate.pdf" rel="nofollow">http://www.jmloveridge.com/cosh/Aluminium%20Sulpha...</a></p><p>------------------------</p><p>If it was me, I would re-use the mixture as often as possible, then set it aside somewhere safe for the water to evaporate, leaving solid crystals that can be safely disposed of at a commercial waste facility.</p>
<p>Wow, super cool! :)</p>
<p>Fantastic Instructable! I really appreciate the detail.</p><p>I might try this, etching my mask with a laser, and using acetone to remove the mask after etching.</p>
<p>Thanks! If I ever get hold of a cnc cutter or laser, I will make so many real cool things. With the laser, be sure to keep your mask thin and uniform.</p>

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