I've been having a lot of fun with this technique, and wanted to share, in case anyone out there wants to try something new! When I first got interested in this, I did a whole bunch of research and found out that there are MANY ways to etch metal - some are extremely high tech and others, like my humble little method, are low tech, easy and don't require any fancy equipment.
So what is etching, exactly? In this case, it is drawing or painting a design in an acid-resistant medium onto metal, then immersing it in a mordant solution that eats away the exposed metal, leaving your design in relief. Glass can also be etched, but that is a different process from this one!
*Clean sheet metal or discs, any thickness if fine but I like 22-24 gauge
*Sharpie permanent markers or other resist (asphaltum varnish, paint etc.)
*Etching Mordant Solution
*0000 steel wool (or other abrasive)
*Liver of sulfur (optional)
*Polishing pads or cloths
Here is my fun, low tech method for etching copper, brass and aluminum:
1. Start with CLEAN metal
2. Draw design with regular black sharpies of different sizes, depending on complexity.
3. Let dry and go over all ink again. And maybe even again. You want a few coats of ink.
4. Stick duct tape to the back and SLIGHTLY around edges of piece. Duct tape does the same thing as the sharpie, it "resists" the acid. There is this stuff called black asphaltum varnish too if you want, but it's messy and takes a long time to dry. Rio has it here: www.riogrande.com/MemberArea/ProductPage.aspx?assetname=118104&page=GRID&free...
5. Immerse completely in mordant solution in glass container (buy here: www.riogrande.com/MemberArea/ProductPage.aspx?assetname=118108&category%7Ccat...)
6. Leave for about 2 hours. If it's warm where you live, less time may be necessary. You can check the etch in progress by removing the item, rinsing it, and then scratching it with your fingernail. You'll be able to get a feel for how deep the "cut" is this way.
7. Carefully remove items (not with fingers!), wash in sink with soap and baking soda, put baking soda in acid solution (which will foam up)clean and discard in paper towels in the trash. (if it's used up and won't etch anymore...usually you can resuse a few times first). Store in glass container with secure lid if saving for reuse.
8. Use 0000 size steel wool to scrape off sharpie and clean again
9. Liver of sulfur if desired and then polish off with pro polishing pads (or whatever)
And that's it! It's easy and fun!! If you want a deeper etch, just leave it in the acid for longer. You can also get etching fluid from radioshack here: www.radioshack.com/product/index.jsp?productId=2102868 that is supposed to work well on copper. The Rio stuff is for copper brass and aluminum. If you want to etch silver, you will need nitric acid of ferric nitrate. You can get the silver solution at Rio also. Ready to go "all out"? You can get a neat system that doesn't use acid from here: www.sherrihaab.com/etch/