Etching Sterling Silver
You may be asking yourself why to etch sterling silver and not just silver. Well, pure silver sterling is not as strong as sterling silver. The other thing is that pure silver does not accept a patina, therefore getting a patina finish from it is quite difficult. The process of etching silver is long and requires several days therefore it is expensive too.
Sterling silver can be etched using ferric nitrate, this chemical is much safer than nitric acid, but it does not mean ferric nitrate is harmless, it is a corrosive chemical to avoid contact with your skin especially your eyes.
Ingredients
The following ingredients are needed to etch silver successfully. Distilled water, ferric nitrate, and nitrate solution that was used in the previous etch are important for offering a kick start, you finally need to make a nitrate solution by dissolving the ferric nitrate crystals in water. While stirring your content, the plastic spoon is highly recommended. CAUTION: use protective gear such as wearing rubber gloves and safety goggles. Incase silver nitrate reaches your skin, wash with baking soda solution to neutralize it. Always perform your etching process in a fume chamber, silver produces fumes when etchant is working on it.
Other requirements include; permanent marker pen, PnP paper clear cello tape, resists film which is more efficient than pen ink as it stays long inside the etchant.
The Etching Process
The first thing you need to is to do enough preparation for everything that is needed for the process to be successful. Prepare the design that you want for your silver, transfer that design to a PnP paper using a photocopier machine. The photocopier should be set to give your design as much contrast as it can. This design image will act as a resist. Photocopiers should be able to use carbon-based ink because they are easy to transfer the image from PnP to the metal.
Next, you need to cut your metal, use a metal shear to cut your metal, and ensure the size of your metal exceeds the size of the PnP paper. Place your PnP paper on your metal and apply moderate heat to it. The image will then be transferred to the metal and now the PnP can be peeled out of the metal surface. After this step, the preparation is done and now the next step is etching.
You need to protect the rest of the metal parts that are not going to be etched, for example, the edge of the metal and the back. You can use an acid-resistant substance such as nail polish to cover those parts. You now need to put on your protective gear like gloves, aprons, and safety goggles.
the next step involves pouring the chemical you are using into a plastic or glass container, for example, ferric chloride. Immerse your metal into ferric chloride and leave it for some time depending on the depth of your etching. For example, 1.5 hours for deep etching and 30-45 minutes for shallow etch.
Finally, remove your PnP resist and clean your metal using soap and water to remove any residuals. Your metal is now fully etched and the final product is smooth and attractive silver finish.