October 11th, 2006
|05:08 pm - A finished commission!|
haikujaguar contacted me a bit over a month ago about making a pendant for her. It's a significant one, since it depicts the name of the main character in a book she's writing, so I was pleased and honored that she asked me to make it for her! But before I go on about technical details, here are a couple of pictures:
The first one is one she took, after adding the tassel to the bottom loop; the second is the one we took right before sending it to her. The design is her copyright, of course! And you can read more about it here, in her journal. :)
We had originally discussed casting as the method for turning her art into the pendant, but ran into some problems. It's a big piece- 1 inch x 3.125 inches (2.5 cm x 7.8 cm), and in general, casting works best when there's more volume and less surface area, and is less effective with large, flat, relatively thin pieces (16 ga. in this case, or 1.3mm). I did discuss it with the casting outfit we normally use, and it just did not sound like it was a great idea. Possible, yes- but far from ideal.
So then I thought of etching. I'd done silver etching before, but many years ago. I did have the materials and equipment to do it, and had been meaning to experiment with it again, but had not gotten around to it before this came up! (This is one of the reasons I like commissions- most of them do tend to push me a bit technically... or at least give me the impetus I need to pursue a technique!) A teacher I'd had a long time ago, however, swore that the etching process released very toxic gasses, so I felt that doing it outside was the only sensible course. We experimented with different ways to best apply a design I had as a digital file to metal, settled on one, experimented with various settings for the electrically-assisted etch, and were ready to go! I used a dilute nitric acid solution and a titanium plate as the other node (and I will not begin to guess whether it was the anode or the cathode; I get horribly confused!) And I brushed up on my chemistry a bit, and as best I can figure the only gas it throws is hydrogen (and not much of it)- so as I said at the time, I think that as long as I don't store it in a zeppelin, it's pretty safe. I'm glad I can do it indoors from now on!
haikujaguar and I had discusses the metal for this pendant, and we settled on the argentium sterling silver alloy. It's a bit whiter than regular sterling to my eye, far more tarnish-resistant, and can be heated in a kiln to make it stiffer and stronger than ordinary sterling gets. All these qualities made it attractive to us both, so we chose it.
There was not much documentation of etching on argentium, but what i could find said that it etched just like sterling. And mostly I will confirm that; one difference is that the argentium seemed to leave a somewhat textured surface where it etched away, but it's an attractive one and makes a nice contrast with the smooth, unetched surface. (The pendant, by the way, has the background etched away from the figures, not the figures etched into the background.) I started with 16 ga./1.3mm sheet, and etched away about 0.3mm of it. I didn't want to go much deeper, because 1mm/18ga. sheet is a good thickness for a flat pendant that size, in my opinion- it's heavy enough to feel substantial and hang well, without being hard to wear.
We'd also discussed the loops and the bail. We settled on a half-octagonal loop shape, reflecting the clipped corners of the pendant itself. Since a small bail would slide back and forth on a longer, straight-topped loop, we chose a tube bail that was the length of the straight part. The pendant will probably eventually have a steel chain, and I picked a fairly heavy tube, to better withstand such a chain; I also did not flatten the tube at all so that its rotation will even out any wear. (This tube is the one part of the pendant that is not argentium; I have not yet found a source of much argentium tubing.)
The loops themselves were assembled with fusing, not solder. Argentium fuses beautifully! And I have had some concerns about the color match between argentium solders and the metal itself; it's not as close as silver solder is to sterling, so I wanted to minimize its use. Each loop started out as 5 pieces that were carefully cut and filed to shape, then fused together in 4 steps. After that, and the etching, I threaded the bail onto the top loop, checked VERY carefully to make sure I had the pendant right-side-up, and soldered the loop-with-bail onto the top, and the other onto the bottom.
I then heat-treated the pendant to harden it, then patinated it with liver-of-sulphur. The patination would mostly be removed during polishing, but it would leave traces around the figures and so make them stand out more visibly. LoS is an interesting thing to use on argentium: the metal colors far more slowly than sterling or fine silver, which would allow one to better be able to grab some of the fabulous, oil-slick colors that a very light application of LoS can produce. Cool!
The pendant has a fairly heavy scratch finish on the back- it looks nice and is easy to maintain, so I often use it on the backs of pieces. On the front I gave it a light scratch finish all over- this removed the patination from everywhere but the edges, made the background look whiter, and acted as a pre-polish for the figures themselves. I'd hoped to be able to polish the figures with a hard felt buff, running it just over the unetched parts without hitting the background, but that didn't work; it ended up polishing the background too, in the larger areas, and I didn't want that. So I took very small polishing points, in fine and then superfine grits, and carefully went over every line of the artwork to shine it up. It took a while, but I think the results are worth it! The shine of the symbols (and the bail) plays off well against the matte-finish background, and helps the symbols to be visible when lit by a variety of angles.
What's liver-of-sulfur when it's at home?
A quick search finds it described as "Sulphurated Potash". It is, basically, the same chamical that makes rotten eggs and swamps stink. It also tarnishes many metals quickly, and so can be used to give an "antique" look- and sometimes, if you're lucky, get some really wild colors. :)
It's called "liver" because visually its texture looks a lot like liver.
This is fascinating! Thanks for so much detail. :)
This is the place where I feel free to get my total metals geek on! I figure people can skip over the stuff that makes their eyes glaze. :)
I agree! And it was nice to read how working with argentinium differs...I haven't done much research, but I was thinking of picking up some wire to play with.
This is deeply cool! Question -- what does fusing entail?
I believe technically it's a version of welding, just as what we call "soldering" is technically "brazing."
Anyway, it involves heating a susecptible metal just to its melting point, at which tie 2 tightly-fitted pieces will join together into one seamless one. It's most usually done with fine silver (99.9% silver) and high-karat golds (usually 22k+), since these don't develop oxides with heat that would prevent the molten metal from joining together.
Argentium is interesting this way, since it's 92.5% silver- a sterling alloy- but it fuses even more easily than the fine silver and gold. Since it's a lower-percentage alloy, its melting point and its flowing point are different (with pure metals they're the same- it goes from solid to liquid, so one has to be fast and precise). With argentium, it gets 'wet" but holds it shape for a while- that's what a different melting and flowing point means- so the process is more forgiving.
it looks amazing! isn't fusing argentium so much fucking fun?? i discovered it by accident and was enthralled. /nerd
Thank you! :)
I love fusing argentium. One of the things I want to play with is using it for granulation, starting with using fine silver granules (since i already have those!). I did start a loop-in-loop argentium chain a while back- I got the links fused, but need to get back to it.
|Date:||October 12th, 2006 07:51 am (UTC)|| |
How long did the etching take? Didn't you get 'under-etching'?
Underetching is an issue when etching PCBs, and that is only a few micrometers of copper -- I'd imagine that it would be even more of a factor in this pendant.
The etching took maybe an hour- after I got the electordes on the right nodes! I was guessing, and naturally guessed wrong. I need to lable the machine...
And no, there wasn't undercutting, or not to signify. That's one of the amazing things about this whole approach- it does seem to minimize the undercutting. When I first did it, we used (as best I recall) a 3:1 water to conc. nitric acid ratio, and one of the really BIG 9-V batteries. Usually, the first week we used the acid we did have some undercutting, but after the acid had gotten "used" a bit, that almost vanished. I'd initially made up a 4:1 ratio for this reason, then read about someone else's experiments using (I think) a similar piece of equipment instead of the battery, and she was using a 20:1 ratio, a VERY weak current... but it was taking several hours. That seemed a bit long, especially for experiemnts, so I split the difference, diluted my solution to make it 8:1, and we did crank the power. Worked great! There might have been a bit of undercutting on the initial one, but none that I could see on the pendant.
I have NO idea why this works! But it does, and I am grateful. :)
|Date:||October 12th, 2006 08:00 am (UTC)|| |
I think that as long as I don't store it in a zeppelin, it's pretty safe.
Haha, that was fun!
Argentium sounds lovely. Sigh that I don't have a jewellery workshop. I miss is to often. We did tubing at school and it wasn't too difficult, and if the argentium fuses to itself, wohoo!
|Date:||October 12th, 2006 08:01 am (UTC)|| |
Btw, I think the piece looks lovely and the etching very precise :) Did you paint it on? what did you use?
We used a vinyl film and removed it with a computer-controlled laser, actually. :) It does give a very precise mask, though the glue that doesn't QUITE come off is something of a problem. We're looking into other options as a result. Like, we might experiment again with spray paint...
Getting artwork from the computer into 2.5D metal has been an ongoing challenge for us, and we've explored a LOT of options along the way at this point!
I swear, you're the only person who got the joke, in bad taste though it was. :) Thank you!
I think argentium would be pretty cool to use for wirework. And since you have a kiln, heat-treating it wouldn't be a problem, so you'd get both the tarnish-resistance and the extra hardness.
So far it doesn't work for enamels, by all accounts- that's its one big flaw where I'm concerned. Well, that and the bad color match for the supposedly matching solders. :( Still, it's really nifty stuff!