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.