Monday, 17 March 2008

The Up-side of lousy weekend weather

Despite a few spring-like days last week, it turned filthy for the weekend (natch!) so the jungle will have to wait until next weekend before being tamed. We descended into the cellar, where we did silversmithing.

Jenny is struggling with an amber necklace which came apart a while ago, and which I made worse when I tried to fix it. She's now replacing sundry bits with silver, but it's not going smoothly, not least because she needs to drill lots of 1mm diameter holes, and all my tiny drills seem to be completely blunt. It's a well-maintained workshop, oh yes!

I, on the other hand, had considerable success, as the pics demonstrate.

The 'face' tie slide is loosely based on a mask made by the Fang people of central Africa, places like Cameroon, Gabon and the Congo, I think. Here's a link to some pictures of African masks.

The other one is supposed to be Acanthostega, a beast whose fossils we brought back from our expedition to Greenland in 1987 and on which most of Jenny's subsequent career has been based. It's a brooch with a safety chain. Jenny has lost enough brooches that I've made her, that these days I generally add a short length of fine chain with a hand-made safety pin on the end.

The reason I'm so pleased with myself is that I've finally cracked a technique for casting silver at home, and that's real progress. It has its idiosyncracies, but they'll get easier to deal with as I gain experience.

It's called cuttlebone casting, so you raid the local pet store for cuttlebones, then you saw one in half lengthways to make 2 thin sheets. Carve the shape you want to cast into the cut surface of one sheet, cut a funnel shape to pour the silver in and then put the 2 halves back together and bind them with thin wire. Balance it upright in a dish of wet sand (in case you spill the molten silver) then pour the silver into the funnel and hope it's OK.

The first picture to the left is a couple of cuttlebones, as I'm sure you've seen them in pet stores. The other picture is of 2 bits which show something of how the process works. The lower one was a failure. The silver wasn't properly molten, and a lump fell in and blocked the funnel, so you can still see where I carved away the cuttlebone. You can also tell that the cuttlebone is only just man enough for the job, and after one pour, it's scrap.

What I'd had difficulty with before was what to melt the silver in. Years ago I spent proper money on a high-tech ceramic crucible, but it was too tall and narrow for the flame to get to the bottom and I never succeeded in melting the metal properly. And it was difficult to manipulate when hot, lacking a handle. The other weekend at Bringsty Art Studio, Ian Buckley showed me what he uses - a simple stainless steel kitchen ladle. So Jenny bought me one, and it's a dream. The silver just melts under the flame and the handle stays cool enough that I can hold it in a gloved hand to pour. So simple, it's just great!

The hardest part is carving the shape you want to cast, because, of course, that has to be in negative, which is a difficult art to master. As you can probably guess, since neither casting above is all that close to how I intended it. But a big plus is that the cuttlebone has striations laid down when the animal was growing, and these appear in the final casting. The striped texture on both pieces is entirely down to the nature of the cuttlebone, and adds an interesting random dimension to the end result. I guess the skill is in learning how to exploit that to better effect.

Oh yes, and make sure the ventilation is good, otherwise the house is filled with the stink of burned cuttlebone. Lovely!

8 comments:

Blogget Jones said...

Wow, this is fascinating. I had no idea what this process was....thanks for educating me!

:o) BJ

Rob Clack said...

Hi BJ and welcome to my blog. I've always found making things and fixing things completely fascinating (although sometimes completely frustrating!) so although I started writing the post just showing off what I'd made over the weekend, it turned into explaining how I'd done it, simply because I realised most people would never encounter that kind of stuff in their lives. So I added extra info and photos in case anyone was interested. Glad I did!

ArcticFox said...

The process of sculpture and of carving negatives for casting is completely mindbending to me.... I used to work in a huge valve manufacturing company and their foundry and castings were an amazing sight to behold.... they used to make valves big enough to stand up in!! I guess you'd need the mother of all cuttlefish for that little trick!!

Me, personally, I prefer my cuttlefish alive.... they're beautiful creatures the way they strobe their colours.

Your silver work, as ever, leaves me in awe!!

FoX

Rob Clack said...

Thank you, FoX. And I agree about cuttlefish. They are amazing to watch and it would be a real high point if I ever saw one when snorkelling.

Manufacturing processes are always fascinating, especially the really big stuff. I use to work for British Steel in Redcar, and walking around the rolling mills was fantastic. The noise, the heat, the sheer presence of those enormous machines and ingots of steel. Wonderful! Your giant valves conjure magical images, especially the giant cuttlefish!

But Why? said...

Nice work!

I am most impressed - I had no idea you were such a multi-talented fellow!

...and just what does burned cuttlefish smell of??

Rob Clack said...

Tricky. Somewhere between burned (feathers, bone, hair, shell) but probably not as strong as any of those, apart from possibly shell, since that's the only invert one. Long time since I remember smelling burned shell, so hard to compare.

btw It is true I do lots of things, but it's also true that I don't make that much time to do any one of them. eg, you (BW) row and train almost your entire non-working life, as far as I can tell. I do a tiny bit of each of about 95 different things instead. I'm crap at all of them, but I find it terribly interesting doing all that stuff, while you adore focussing intensely on those few things. We each love what we do, and wouldn't do it any differently.

Blogget Jones said...

I'm glad too, Rob! I love learning something new :o)

Sparx said...

I am so damn impressed! I've always wanted to work with silver but never had the time or energy to learn how... you make it sound easy.

I'm another 'jack of all trades' which is sad in some ways as I would love to be an absolute mind-blowing expert at at least one thing... but 'tis not to be!

No, can we have something on what you use (apart from the ladle) to melt the silver? Presumably it's not just a candle flame!