My latest passion (aside from my husband) is metal etching. I am so obsessed that I even cut up some brass charger plates (flea market finds) and am etching and making jewelry from the brass. I’m using copper too.
I started my etching explorations with ferric chloride, which you can buy as PCB Etchant at Radio Shack. Rumors abound that Radio Shack no longer sells this. It’s not true. Much to my delight, however, I found you can purchase ferric chloride for half the price at Dick Blick.
Ferric chloride is not acid, but you don’t want to get it on your hands, clothes or in your eyes. I wear gloves and eye protection when I use it, and I work in a well ventilated room.
After scouring or sanding your metal to make sure it is free of tarnish, dirt and fingerprint oil, you put an image on it that will resist the ferric chloride. In othe words, the ferric chloride will eat away whatever you did not cover with etchant resist. Sharpie permanent markers provide an effective resist as well as Stayz On Ink which enables you to use your favorite rubber stamps. Sharp black and white images work best. Another method is to photocopy or laser print your images onto transparency film sheets and iron the image onto the cleaned metal. Transparency film is expensive. I have had success with the backing for a sheet of labels made to be printed with a computer. If you work in an office, ask people to save these for you instead of throwing them away. I print the image on the side of the sheet where the labels were and iron it onto the metal, image side down.
After you prepare your metal and fill a glass or plastic container with a couple of inches of ferric chloride, you cover the back of the metal with packing tape and suspend it, design side down, into the solution. Why? The etchant eats the metal and metal fragments flake away. If the metal was right side up, the fragments would sit on the metal and interfere with the etching process.
When you remove your piece from the solution, neutralize it with baking soda or ammonia, rinse well with water and clean off the resist. The time you have to etch depends on how strong your solution is (e.g. how many times you’ve used it). Ferric chloride, which is a salt and not an acid, is considered a slow etchant, so your etching time might run from 30 minutes to several hours. You need to check your metal from time to time until you know what to expect.
You can reuse the etchant until it’s too weak to perform. Then you must dispose of it. Don’t pour it down the drain. It contains metal fragments and you don’t want to add them to the water supply. Contact your local government authority for instructions on how to dispose of hazardous materials.
I learned of a great alternative to ferric chloride works faster and eliminates those pesky metal fragments. It’s called the Edinburgh Etch and it’s composed of ferric chloride and citric acid. Citric acid is a natural substance found in citrus fruit and many soft drinks (It’s not just the sugar that rots your teeth.) I have seen many complicated formulas and equations for mixing ferric chloride and citric acid. I mix 4 parts ferric chloride to one part citric acid. The citric acid is composed of 3 parts water and one part citric acid by volume. Translated, this means 1 cup ferric chloride (16 oz), added to a mixture of 4 oz citric acid. You mix the citric acid by adding 1 oz powder by volume to 3 oz water. Increase this formula to get more etchant solution. You can buy citric acid on ebay. For more information on metal etching, go to Makers Gallery, Ganoksin, etsymetal and DIY Network.
Next week I’ll post some pictures of my etched metal.