Tinkerings of a sculptor and metalsmith...: Making & using plaster gems with PMC

2009-11-23

Making & using plaster gems with PMC

Although CZ and many other gemstones can be successfully fired into PMC, I often find that the brilliance (at least of CZ) is slightly diminished by this process. So I made a flexible rubber mould of some 5.5x5.5mm CZ hearts, then cast the pavilions using a fairly hard casting plaster. Each tended to have a small missing piece at the point of the pavilion due to an air bubble, but this proved not to be a problem. When well dry, they were embedded at girdle height in plastic PMC shapes (themselves embedded in flexible rubber moulds), the whole de-moulded, dried and fired at 800C. This higher temperature possibly helped to denature the plaster sufficiently that it was easy to clean out from the cured (i.e. sintered) PMC. It would only remain then to set the coloured CZ hearts using a spot of glue. However that is not what I actually did - on a whim, I melted dichroic glass fragments into the heart-shaped cavities in some samples of the uncured PMC, whilst also firing some 15mm PMC heart shapes with 5.5mm heart-shaped coloured CZ embedded in the uncured (unsintered) silver. In the side-bar to the right, you will see examples of the fired-in-place CZ (right-most two hearts, amethyst and orange respectively) along with the left-most three specimens which had variously coloured dichroic glass pressed in them while red-hot and fluid.

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Setting - advanced course

Another Staff Development course financed by Central YMCA, was an advanced course with Niall Paisley run at Holt's Jewellery School in Hatton Garden. The course was at the end of February in 2007, three full days 9am - 6pm, and covered pave as well as bezel and prong. There is some information on the tutor at http://johnnyrocketltd.com/niall_paisley.php There were only 6 or 7 attendees, and most were in the industry to some extent or other; either employed in jewellery workshops, shops, or in at least one case, starting up a manufacturing company. And one young man had had several years training as a goldsmith, but was currently working as a central heating engineer. However, he hankered for a return to his earlier vocation. One of the highlights for me was that I was unofficially awarded 'course best' setting of a tube-set CZ, although my pave will take a lot more experience.

Maybe egg heads like domed rings...

The domed copper rings pictured above were each made in three parts, in the form of an inner plain band and an outer pair of domed half-hoops. These elements were soldered together and then polished to give the finished result. Usually my sense of purpose is more or less exhausted by the time I get to taking pictures, but I guess you could always say the reflections of my fingers give added interest... The left-hand ring has also had a sort of duck-foot motif etched in a meandering fashion round the outside, maybe I still had egg head on my mind (they were intended for an intellectual friend).

Insight into Lapidary

This course was financed for me by Central YMCA as part of my Staff Development, and ran in October 2005. It consisted of an intensive one-day course in the lapidary workshop of Holts in Hatton Garden, London and was run by Roger Dunkin.

Pieces of hard stone (varieties of quartz etc) were dopped to a stick, then ground and polished with rotating diamond and carbide laps. I managed to end up with a big blister from accidentally touching the hot dopping wax, but also took away a nice lacy agate cabochon, together with a small (4cm) carved and polished quartz cross. The workshop was very well equipped, and I will be tempted to sign up to a future facetting workshop.

From rough as a rasp... to smooth as glass

When I first started making and etching copper rings, I was entranced by the attractive patterns I could get. Subsequently however I found that the sharp vertical edges of the etch were very rough on the skin when worn even for limited periods of time, and even after the ring had been tumbled with abrasive for some hours.

I found that the raspiness was completely cured by enamelling, using the traditional techniques of melting coloured glass powder into the etched cavities. Unfortunately, since I used opaque enamel, this also robbed it of the original dynamic appeal. I feel that if I expend enough effort using transparent enamels instead, it will bring back some of the missing life. A student ring which was pierced through to give a pattern round the entire band was similarly rough on the skin; this was partly cured by fitting a fine silver liner.

No, I haven't entirely got it out of my system...

... but there's hope yet. The top two were done with coloured pencil on black paper sometime in 1985, around 3' x 4', later I tinkered with a more golden-tinted version. Reminds me of art work for the cover of a "DiscWorld" novel. The others are variously unfinished sketches done around 1990 probably. The young lady is Anna Kavanagh who was renting at Studio Place at the same time as myself. All these sketches were found heaped on the floor in a cupboard, and seem to have lost a lot of their pigment.

Some more pastel work from the eighties...

...well, that's what we did, while waiting for ipods and mobile phones to come along...As mentioned above, much of the colouring pigment seems to have ended up on the floor along with the dust. The first picture was actually a second version; I did the first on pastel paper and gifted it to Isabel Langtry, then sculptor in residence at Central YMCA. This second version was re-coloured onto a B&W photocopy, and there wasn't enough 'tooth' on the paper to take the colour. And I remember that the picture with the cluster of figures arising from the waves was used as a sketch for a version re-done on board. The fifth picture was a composite made from photographs of figures in the Foro Mussolini (now Foro Italico), and the last is a sketch I made of Stephen, my partner since 1983, in the first months we met.

Stone setting course

I took a 5-session stone setting course at Central St Martins in February 2005, financed by Central YMCA as part of my Staff Development. It ran in the evenings and was spread over five weeks. The tutor, Martin Hopton, was well experienced both at stone setting and also at expediting the learning process for all students. I think there were only two other males on the course, the remaining 5 or so were female and mostly in their twenties and thirties. The jewellery workshops at St Martins, although somewhat old-fashioned looking, were very well equipped, and especially good on traditional equipment.

Glass Fabrication course

I took a glass fabrication course with Julian Ewart and Helen Maurer as tutors at Central St Martins on 6th August 2001, financed as part of my staff development by Central YMCA. The course featured both slumping, fusing and etching of glass and resulted in a large number of pieces which I took away with me. These included the red-glass etched 'Jelf' logo and the screen-printed and embedded Greek Key design shown further up this column. I also did several versions of a seahorse pressed into powdered plaster, the resulting bed used as a slump mould for glass of varying colours and types.

Glass casting course

On 14th August 2000 I took a glass casting course at Central St Martins run by Aron McCartney, who was at that time still working on his PhD thesis concerning ceramic shell casting of glass. The course was financed as part of my staff development by Central YMCA. The course was somewhat of a disappointment for me for the first couple of days since it was organised around first making a ceramic shell bronze, something I was well familiar with. The subsequent casting of glass into a lost-wax mould lined with plaster was more interesting, I still have both the bronze and the glass casts. I remember picking out bits of castable lead-crystal glass from a large coffer until I acquired enough bits to cast.