Christine Cox

Archive for January, 2017

Metalsmith: Ferric Chloride Exhaustion

For decades, I’ve been etching copper, brass and nickel-silver with ferric chloride (FeCl3), an industrial ferrous salt normally used in water purification and sanitation.

If you’re using ferric chloride, you may wonder how you can tell if it’s exhausted. How often you etch, which alloys you etch, and how large your metal pieces are all affect how long the etchant will last.

The first clue that the etchant is approaching the end of its usefulness is that the pattern you’re etching will be shallow, meaning that etching process will take longer and longer as the ferric chloride gives up the ghost. Nickel-silver presents an interesting side effect when the ferric chloride is exhausted. When you pull the metal out of the etching tank, it will be coated in a brown film. This film acts as a resist and the piece will never etch without the coating being removed, and then re-etching the metal again in a fresh tank.

Of course, we don’t want to waste a piece of metal and all the time to prepare it only to have our exhausted ferric chloride let us down. Another good way to test the ferric chloride is to judge the color. From the accompanying photos you can see that new and exhausted ferric chloride look very similar, but study the pictures closely and you’ll note that there is a slight difference in the overall yellow tone. The new liquid is a reddish/yellow, while the old, used up liquid is a greenish/yellow.


The cup on the left contains new, unused ferric chloride. The greenish/yellow liquid on the right is headed for the dump.

New ferric chloride (reddish/yellow)

Exhausted ferric chloride (greenish/yellow)

Bottles of ferric chloride that have been neutralized and are headed for the dump

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Metalsmith: Straighten a Crooked Balled Rivet

(A typically occasional series by Christine Cox)

Balling up the end of a wire for rivets, findings or decorative elements is one of the first things a metalsmith learns. It’s a fun and rewarding activity, though there’s a bit of a knack to it. The wire needs to be in the hottest part of the flame. You can’t dwell too long or stop too early. You can’t stop part way through and then resume without lowering the odds of success. Always hold the wire straight down so that gravity can help.

In spite of our best efforts, sometimes there’s a problem:

  • The ball doesn’t form or only forms a little (too short a time in the flame, too short a wire, holding pliers too close to where ball should form, too large a wire gauge to heat ratio)
  • The ball isn’t round (probably too long in the flame)
  • The ball falls off (waaaaaaay too long in the flame)
  • The ball is pitted (using the wrong part of the flame, or an inferior alloy such as brass)
  • The ball is on the side of the wire (either too short in the flame, or not holding wire straight down)

That last one can be frustrating, but it’s easy to fix (mostly).

Take a look at the photos accompanying this post. In the first photo, a sterling silver wire has its ball off to the side. In macro terms, the fix is to grab the ball in a pair of pliers and bend the wire until it aligns with the ball. Unfortunately, you would likely end up with a ball crushed by the pliers and a bent wire that still wouldn’t line up.

Let’s take a micro look at the fix.

The crushed ball would be caused by using steel pliers. The jaws on a pair of brass or nylon-lined pliers are softer than steel. Hold the ball in a way that gives you access to the exact spot where the ball and wire meet.

Now place your finger where the ball meets the wire and bend the wire until it lines up. If your wire bends anywhere other than at the point where it meets the ball, you need to put your finger right up against the ball.

That’s it! Now, go back through all your old balled wires and see if you can fix any of them.

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