Safe Metal Etching: Be Fearless, Be Wise, Be Responsible
The last time we covered metal etching on Jewelry Making Daily, a few folks commented that it was too dangerous and asked if there was a safer way to etch metal. I’d heard of some alternative methods and I had some ideas of my own about homemade concoctions, so I consulted a group of very wise metalsmiths in a metalsmithing group I’m part of on Facebook. Oh my, did they educate me!
I asked if anyone had experience with a safe or at least less dangerous, nontoxic way to etch metal, maybe using household items that seemed like they might work, such as lemon juice, nail polish remover, or a mixture of vinegar plus something–that always seems to be a handy household combo that can work wonders, so I thought it might be worth a try. One reader suggested using the brown soft drink (you know which one); I hear scary stories about them cleaning toilets and dissolving nails, so they probably would work. I’ll have to experiment with that one.
Silliness aside, I learned two important points about metal etching from all those wise metalsmiths.
The first was this: Ferric chloride, which is what most folks use to etch copper, isn’t toxic* or super dangerous–it’s a salt. Not an edible salt, of course. You shouldn’t drink it, you shouldn’t get it in your eyes, and if you get it on your skin, wash immediately. Use it in a well-ventilated room. But you can use it without being fearful.
* Update: I want to add to this to be perfectly clear, since we’re dealing with such an important topic. Ferric chloride is dangerous if you ingest it or get it in your eyes. In that sense, it can be toxic. But if you use it properly, and store it properly, you should be able to do so without fear. If you get it on your skin, wash it off immediately and well. When I said above that it isn’t “toxic or super dangerous” I was referring to toxic in the common, toxic-waste sense–a term that people use to describe things you don’t even want in your neighborhood, let alone in your house. But if, to you, toxic means it will make you sick if you ingest it, then yes, it’s toxic.
“While ferric chloride is relatively safe in regards to burning flesh when compared to concentrated mineral acids, you should still treat it with care as it is very corrosive,” said James Binnion of Mokume-Gane.com (one of the wise metalsmiths in our discussion). He also noted that “in its liquid form, it typically has a few per cent of hydrochloric acid added to it to keep it functioning for a longer period of time. So it should be treated similar to any other mineral acid.” So again–avoid skin and eye contact, avoid breathing fumes, and certainly don’t ingest it.
Properly Dispose of All Etching Solutions
The second thing I learned was this (and it’s big): As much as the etching solutions themselves, you need to pay attention to proper disposal of the spent liquid when you’re done–even if you’re just using saltwater or something equally tame to etch metal. You must dispose of the spent metal etching solutions at a hazardous waste site, which to me makes them seem more dangerous to use than they actually are, so it’s important to understand why they require such disposal.
This is the big reminder I got from our discussion that I often forget: Etching removes small particles of metal, just like sawing and filing do. So where does that metal go? The solution you use–toxic or not–is ultimately going to end up full of tiny particles of whatever metal you etched. So for safety’s sake, first you need to neutralize the etching solution–but you’ll still have all those tiny particles of metal. You can strain the particles from the liquid with a coffee filter, or allow the neutralized liquid to evaporate from the solution, leaving just the dry metal dust remains. (Update: Allowing the liquid to evaporate is the better of the two solutions, because not every tiny particle of metal can be removed with a coffee filter. Better safe than sorry.) But what do you do with them then?
Those metals are natural and came from the earth, so what’s wrong with just dumping them back in the ground? As it turns out, the etching process makes the metal particles more harmful (environmentally speaking) than they were when they were mined from the earth. “It converts them from a metallic form to a metal compound,” James explained. “Metal compounds are typically bio-available, meaning they are readily absorbed by living things, and metal compounds are for the most part toxic. So pouring them into the ground poisons the area.
“The waste from any kind of etching needs to be disposed of as a hazardous material,” James said. “Metals by themselves are generally not a health or environment issue. Once you dissolve them, however, you typically have converted the metal into a water-soluble compound. These are more often than not toxic.”
So while caution is required when working with ferric chloride, finding a “safe” alternative metal etching solution doesn’t free us from all caution when using it or all responsibility when disposing of it.
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