Christine Cox

Posts tagged ‘etching’

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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Book Hardware Class

A couple of weeks ago I taught a class on Gothic-style book furniture/hardware. My student, Kath Thomas, did amazing work! In spite of having a cold, and having never worked in metal before, Kath was quite prolific and produced what I like to call The Thomas Hoard. I have to say, Kath’s energy is inspiring! Great job, Kath!

Check out her beauties.

Kath Thomas Hoard

The Thomas Hoard

1. Etched corners (most with bezel-set stones, one made to wrap around wooden board), 2. Anchor and catch plates (practice),
3. Etched strap with soldered ring for peg, 4. Textured boss, 5. Etched and pierced fastening with bezel-set stone and soldered peg,
6. Shovel strap and anchor plates

Christine is teaching this class again in May, 2013. Care to join us?

 

Etching Silver

Awesome texture from rolling mill

Sterling necklace (reverse)

Elaine K. emailed about etching silver:

Q. I’ve been fascinated with your website and its offerings, but am not sure I am ready to equip my studio for etching sterling silver.  Can I etch silver, either sterling or fine?

A. One can etch silver, but it takes a different chemical and different equipment than one would use for etching base-metals (copper, brass, nickel-silver). Most people use nitric acid to etch silver (either sterling or fine), which can be very dangerous (I burned my eyes a little the first time I used it), and it has a short shelf-life. I etch base-metals in ferric chloride (relatively benign). If I can avoid etching silver, I do. For texture, I tend to either use a rolling mill or else hand-texture the silver with a hammer or flex-shaft. If you absolutely must use nitric acid, please follow all the safety instructions.

Thanks for the great questions, Elaine.

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