Penumbra: Faces

Limestone tile (detail).

Having started this project during the last module, I had already developed a strong message that I wanted to convey and had some experience with the electronics behind the project, now I had to finalise the aesthetics of the piece and write some fully working code.

The overall form of the product had been decided while making the previous prototype, but for the final prototype I had the challenge of selecting materials that best communicated the meaning behind the product.

From the outset I knew that I wanted to use a natural materials in the sundial to echo an ancient celestial/shamanic style.  I considered a variety of natural materials in different combinations; a smooth, chalky white gypsum face with a rough cut slate gnomon; a pale lime mortar face poured around a knapped flint gnomon.  From the chalk-like faces, I progressed to limestone.  Much easier to source and work with, a limestone face also echoes the sentiment of the piece as it is thousands of years old, made of fossilised sea creatures.  The problem with limestone would be sourcing a thin slab at a reasonable price, and cutting it.  I had initially thought that this might be a job for a stone mason, until a friend of mine asked if I could use a floor tile. Finding a natural stone floor tile was easy enough – I went to Topps Tiles and picked the style I wanted – the problem would be processing it and ensuring continuity. 
  
Because natural stone tiles are mined from vast quarries before being split up into smaller units, the colour of the stone varies from tile to tile.  Having bought three tiles in two different varieties, I felt lucky that they all turned out to be on the lighter end of the spectrum.  When I was tile shopping I was struck by the quality of the natural stone; some looked like aerial views of barren deserts, their veins like paths in the sand, while others looked like planets, craters scattered across their faces.  Naturally, I chose the celestial ones, with one tile resembling the moon and the other the sun.

During waterjet cutting

Cutting the tiles was the next hurdle.  The tiles were 12mm thick and because I needed a perfect 35cm diameter circle, the only accurate way of doing this was by waterjet cutting.  The issue with waterjet cutting natural stone is that if the jet hits any inclusions or fault lines, the whole tile can split.  Thankfully the technicians in the School of Engineering were willing to give it a go, and with my fingers crossed I watched as my tiles were cut.  I only needed one to work out of the three (I bought two back-ups just in case but at £15 a tile, I was really hoping for the best), and amazingly, all three worked perfectly. 

Then it was just a matter of choosing my favourite one and making the case for it.