fragile creation

Shelley and I [Scott] had a two-day workshop in Frome with glassmaker Sonja Klinger to make our new glass pieces. We’re writing this several weeks after the event – so rather than a ‘fresh first-impressions’, it’s more of a reflection with hindsight.

The plan for these two days in Frome was to create some new glass piece, designed specifically for this project to afford specific musical mappings. Scott and Shelley were joined by Sila (Shelley’s intern) for two days in Sonja's workshop; and Rex Lawson joined us briefly to see how his pianola rolls would transfer to glass.

We had taken a motif from a Bach fugue (no.2 in C minor) and sandblasted it onto the surface of a glass 'embryo'; a basic glass jar shape. This embryo would have more molten glass added to it so that the sandblasted dots would trap air bubbles under the glass. The images below show the initial embryo, and a subsequent stage where it has just been dipped in hot glass. 

In preparation for this, Sonja had prepared some embryos back in July. Shelley had done the painstaking work of transferring the patterns from the pianola roll onto glass. This involved scanning and adjusting the chosen designs from the rolls, cutting and re-cutting the holes to etch the pattern into glass, then sandblasting and cleaning the glass.

As we arrived in Sonja’s workshop, she showed us the embryos which had been slowly warming up all morning: they warm up because if glass goes straight from room temperature to kiln temperature (over 1000°C) it would shatter. The plan for the session was to take the various embryos, coat them in layers of molten glass (by ‘encapsulating’; dipping into a cauldron of molten glass), and spin them out into flat plates. In this way the etched patterns around the jar-shaped embryo would become a circular pattern on a flat plate, captured beneath a layer of clear class that would trap bubbles where the etched holes were.

Shelley had not done this for nearly two years because it is so expensive. However, for this project it was perfect, because the process of heating glass in a cauldron or ‘pot’ creates the most an extraordinary ‘grain’ in the final object that is only visible with projected or reflected light. This grant made it possible to create work using this technique that suited our goals so well.

The scented autumn day finally arrived. Shelley was was extremely nervous about how this might go. The whole process is almost impossibly precarious, and made even more so by the thin-ness of the glass we required. Shelley describes how she has ‘seen so many hours of hopeful effort crack or fold or fall from the end of a blowing iron’.

And, as it happened, it did almost all go horribly wrong, by Shelley’s original standards at least.

The first plate came out fine. The simple, symmetrical pattern of the etched triplets spun out to create a series of looping curves on the plate. Although clumsy and thick and deeply dipped in the centre, it was at least in one piece; and round!

We tried a second plate, this time in black glass. Rather than using black glass itself, the black is applied as a layer onto clear class. The molten surface of the clear embryo (after dipping in clear glass) is rolled in grains of black glass, which themselves melt and flow into a layer. This particular granularity interacts with light in a wonderful way, revealing a texture that is invisible to the naked eye. The image below (by Michael Coldwell) was captured at our September session in Leeds working with improvising musicians.

After these initial successes, our luck began to run out. The first embryo of Tuesday morning had a complex encapsulated pattern which threw the material off-centre to make a hopelessly ridged and wobbly pancake. In the final heating, the edge of the glass caught the rim of the glory hole to create yet another strange bump. However, under strong light these imperfections have real charm.

The next embryo cracked and fell into the pot of molten glass. Lost. Dear Sonja was so upset that her kind face burned red and her solid assistant Keki stepped in to rake out the bubbly mess.

We started again –  this time to make a plate.

In the next attempt the embryo collapsed but stayed on the iron. Rather than try to retrieve the shape, I asked that we simply let it be, a random looping stone form with my hard-won fugue pattern veering around inside. We decided to stop trying for formal precision and just play. Scott took this opportunity to do some glassworking, to try and pull the glass into a shape that would respond well to the light. The glass shape was quite dense, with the hot glass ‘gather’ loose, rolling and looping like treacle on a spoon, but it was possible to pull the surface to form some gentle twists, creating a beautiful and subtle ‘rabbit’ form.

For the final embryo we opted for a bubble with twists. Now that he’d had a chance to get used to the feel of pulling the soft glass with pliers, he had some specific ideas to try. Scott seemed totally focused, pressing and pulling the material as it slowly came to rest. Sonja blew a bubble (a hollow form which responds more easily to pulling) and added ‘prunts’ (handles) for Scott to experiment with twisting and pressing. The end result was a slightly curved bubble with several twisting ‘knobbles’ on the surface. The twists are barely visible in the glass itself, but create stunning caustics in light (image Michael Coldwell).

Shelley’s intern, Sila also made a piece for herself with patient coaching from Sonja. She has a rare gift for form and edge and we look forward to seeing where she will go.

It was wonderful to get back to the house that evening and test out the new pieces in light.

Reflecting on the whole day, we see this as the event where the project took on a life its own, related-to but distinct-from each of our personal practices. Shelley has described this way of working together as being a ‘level of vulnerability and support that was both new and extremely rewarding. Quite a revelation for me.’ Scott also found that after years of discussing and the ideal, and working together in less than ideal circumstances (brought about by distance, time, and trying to mould the project’s essence around our existing practices and works) this activity of making new glass specifically for the project gives it an independence that has both a supportive force for both of us as artists, and it gives the project a ‘release’, unmooring it from many previous concerns. For Scott especially, the act of pulling and shaping the glass gave him a connection to the project’s materiality that re-oriented his thinking about the musical possibilities. For both of us, this new independence allowed us to relax some of our more discipline-specific concerns about the project. For Shelley especially, the precision and rigour of her usual practice had to be suspended as we experimented with forms. None of the pieces we made in this session will be artworks in themselves, but they all offer something to the project that we couldn’t achieve by using Shelley’s other pieces. Scott’s discipline-specific concerns were destabilised (positively!) later when we brought the finished pieces to Leeds to get some musicians trying them out. More on this in the next blog post.

Waves of rays

What an incredible week – two inspiring meetings with two very different men – one an artist, the other a scientist - and yet so similar in their passion and depth of knowledge – and both so generous with their time and expertise.

Rex and his wife Rhona welcomed my intern Sila and I [Shelley] in their rambling house in Bromley.

We walked through the sunlit garden into a cavernous studio packed to the rafters with boxes of pianola rolls and presses and ancient computers to find Rex playing a grand pianola at full tilt – the piece that he played for their wedding exactly 12 years ago.

Rex explained how the design of the rolls evolved from 64 to 82 holes to allow for more sophisticated coding, and the difference between the European-style round holes and the American squares. He showed us how the additional lines and dots that I had seen in photographs online are used by the player as a guide for tempo and dynamics and demonstrated the surprising degree of freedom that the player can exert on the way the piece is ‘played’ by the machine.

Stravinsky, among other composers, personally supervised the notation and frontispieces for their new works. A stylised phoenix was the logo for one of the most influential publishers, the Aeolian Company. Rex has adopted this for the home page of his own remarkable software that allows him to design new rolls and cut them himself. He demonstrated the process for us, firing up an extraordinary machine with multiple pulleys and levers and a clattering array of hole punching bits.

Frontispiece for pianola roll

Rex' software home page

Pianlola roll hole punch 

Short video of Rex's software in action

short video of hole punch in action


I had not realised that the whole pianola mechanism is essentially a set of air pipes – the holes release the vacuum and collapse a small set of bellows. This movement in turn releases a hammer which strikes the keyboard of the piano placed behind the pianola mechanism. 

pianola pipe system from the back

pianola pipe system from the front

We chose Bach's Fugue no.2 in C minor from the first book of the Well Tempered Clavier. The recurring triplets of the central theme are coded as a distinctive triangular pattern that dances through the piece.

triplet theme

We left the Lawson household with warm agreement to meet again. Rex will join us for the glassblowing session in Frome in September.

In the meantime, I will send him images of the work as it progresses.

The second meeting was very different but equally memorable – I had met Michael Berry through my PhD supervisor several years ago. We had spent a wonderful afternoon at his house in Clifton discussing glass and caustics and he had kindly agreed to help in future projects.

I was delighted that he was able to spend an afternoon with us when he is so much in demand. We all met at Trowbridge rail station and went to a glassblowing studio run by two very talented young glass makers nearby. Neither Michael nor Scott had ever seen the process at close quarters before and seemed to find it fascinating despite the heat.  James made some Prince Rupert’s drops for Michael and showed us their new coldworking space before we went to a pub by the canal in Bradford upon Avon to continue the conversation.

Katie and James with Michael and Scott

Michael with a Prince Rupert's Drop

Scott with a Prince Rupert's Drop

Scott and Michael

Michael and I

I had tried to read anything I could find on the internet about Caustics before meeting Michael but had become hopelessly confused. With his patient explanation, it all became perfectly clear – and brought Scott and my work into sharp focus.

Until now, we had been shining light through a revolving object. This generated rich and complex patterns of light and shade especially when combined with the reflections generated by the polished facets.

This was the heart of our original proposal– to understand these phenomena to the point where we could direct and refine this luminous vocabulary with greater creative intent.  

As Michael explained, caustics are the patterns of light and shade that are generated by a stream of photons interacting with small changes in the angle of a shiny surface. These undulations essentially operate as mini-lenses, focusing the beam to produce rich networks of curves and points.

The relationship between the scale of the topography and the size of the beam is critical to the effect: a small beam such as a laser pointer will be deflected by very small undulations, a large light source such as an LED lamp will be deflected by larger-scale effects. In both cases, a parallel beam is critical so that a stream of photons strikes the glass from the same direction. A spreading or diffuse beam will create spreading and diffuse effects.

We realised that in order to find the clarity and control we were seeking, we should begin with flat rather than curved surfaces. Rather than looking at the projections created by shining light through the piece, the solution lay in the reflections.

We talked until it was time to get the train home – about parallels between waves and rays of light and sound, the power of prime numbers and the principle of natural beauty.

Michael kindly agreed to continue to advise us as the project progressed.

I was so delighted to get back to the studio to run some experiments with mouth-blown plates with sandblasted patterns to see whether we needed to silver the surface - and it seems that we don't need to after all, .

With Michael’s advice on the light source, have started to get some exciting results.

Caustics from a sandblasted plate

Video showing effect of different distances from the light source

Caustics caustics!

On August 17^th we made a trip to Trowbridge to discuss our project with Professor Sir Michael Berry, a physicist who specialises in caustics, the optical phenomena central to our project.

After meeting up with Michael, the day began with a session watching glassblowers at work; something I [Scott] had never seen first-hand, despite working with a glass artist for over a year. We spent an hour at the Devereux & Huskie Glassworks Studio — friends of Shelley’s — and watched them make a beautiful piece of layered blown glass. The process especially fascinated me for its materiality and intense performativity. The three artists worked together to keep the glass at the correct temperature for optimum malleability, and to keep several kilos of molten glass in constant and even rotation to stop it sliding off the blowing pipe. All of this while continuously shaping and pressing the glass into a unique and elegant form.

We also had some fun watching James and Katie make some ‘Prince Rupert’s Drops’ for Michael.

'Prince Rupert's Drop' or 'Dutch Tears'

After this we went for lunch with Michael to chat about our project, especially the nature of the caustic light phenomena, and their relationship to spectral behaviour in sound. 

Michael is Emeritus Professor of Physics at the University of Bristol. He specialises in the mathematics of light focussing, specifically caustics, phenomena that lie in the 'borderlands between physical theories — between classical and quantum, between rays and waves.' If you’d like the details, Michael’s website hosts his many papers that explain the complex maths behind these phenomena. However, for non-mathematicians, he describes caustics simply as the ‘spectacular patterns of wave interference associated with focusing’: common examples can be seen in the shimmering patterns of light on the bottom of swimming pools and clear streams. This older paper of Michael’s explains the phenomena very clearly, and here’s a beautiful example of a cusp caustic in very fine detail (from Michael's site), and a diagram of caustic formation (from paper cited above).

Talking with Michael changed the way we think about some of our project, or if that's too radical, the conversation at least provided us with another way of thinking about our materials. The primary point for me was that it's possible to generate caustics that are more 'pure' (see below) by removing the refractive aspect of the glass from the equation.  'Pure' here means an image that is only the caustic rays, avoiding multiplying of the image by glass refraction and internal reflections. This is not necessarily the best approach for the project goal of developing a visual grammar for a graphic score, but it certainly provides another aspect to that grammar, another voice. 

The simplest way to do this within our project is to use silvered glass, this allows us to reflect directly off the silver and allowing the curving of the glass to generate the caustic focussing. We can then also contrast that against caustics generated by shining light through the glass, wherein the cording of the glass multiplies and distorts the caustics. Both of these cases provide rich visuals with clearly identifiable elements

A second new element is to trying using laser light as well as white light. Our previous performances have used tightly focussed white light, which gave us good results, but seeing Michael's work with lasers has convinced us to try this approach as well. I've done some experiments using a simple laser pointer, with good results. The patterns from laser light are slightly different (apart from the very obvious difference that they're bright red...) but I haven't yet become familiar enough with them to properly define the different quality: watch this space... Here's an example:

As well as these direct impacts on the project, it was also fascinating to talk to Michael about aspects of chaos theory in his work, as this had a strong influence on my PhD work. I hope to have the chance to chat to him again as the project goes on.