Christine Cox

Posts tagged ‘copper’

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: Twist to De-Bur

Metalsmith: Twist to De-Bur
(another installment in a typically occasional series by Christine Cox)removebur-done

After drilling in metal there is often a large bur around the hole. It’s unsightly, dangerous and can throw off how your piece goes together. Eliminate it easily by using a drill bit that’s larger (by far) than the hole you’ve drilled. Chuck the large bit up into a pin vise. Place the metal, bur side up, onto a surface that allows the tip of the drill bit to drop down through the hole. I usually just place the hole over the V in my bench pin, or slide it off the edge of the bench, whichever is easiest. Press down firmly and twist to remove the bur. Caution, don’t go all the way through or you’ll be left with a hole much larger than you intended. Lightly twist back and forth a couple of additional times to clear the swarf and you’re done.

This is also a quick and dirty way to create a countersunk hole. Just push down a little harder as you twist to get the characteristic flared out edge around the hole.

removebur  removebur-dtl

Available from Volcano Arts:


Metal stock


Small pin vise

Metalsmith: Hardening Sterling

Great question in my email this morning:

Natalie: I recently ordered a wood base steel bench block from you, and am so in love with it! I’m now looking to upgrade my hammer for wire hardening, as I’m finding that the finer wire (28 gauge and smaller) is not hardening well with my current plastic mallet. Would your rawhide mallet do the trick, or is there anything else you would recommend? (It would be a bonus if the rawhide is quieter than the plastic too, since I work out of a home studio and have a 4-year-old). 🙂

Christine Cox: Yes, our rawhide mallet is what you want! When they are new they are a little stiff, so they can be noisy. As the hammer wears in (a desirable trait) it gets quieter. You didn’t mention what alloy you’re using, but if it’s sterling, you can bake it for about an hour at 600 and it will increase the hardness. Copper and fine silver don’t really harden much.

Rawhide mallets are here:
http://www.volcanoarts.com/cart/metalsmithing/index.htm#rawhide

You might want to consider a pounding mat to help quiet your hammering. Put your bench block on top of it and then you don’t have wood smacking wood while you hammer:
http://www.volcanoarts.com/cart/metalsmithing/index.htm#pounding

Thanks for your inquiry. I hope this helps.

Cheers!!!
Christine Cox
Volcano Arts
www.volcanoarts.com

Soon to be an enamel switchplate

Today we’re making enameled copper switch-plates. Check out those tiny pieces of wire. In spite of bad eyes, years of chain maille has made me love detail work like this.

20120406-114216.jpg

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