Colin Rennie

Glass and Digital Artist


My current work is an experement in blending Hot glass craft skills with digital skills.  Capture is an example of a piece that, for me, has been seminal.  The piece exists both in a virtual space and as a real sculpture simultaneously, this dual state poses questions about which came first, the model or the object?

The meaning of Capture is manifold: it can relate to capturing of the glass as a piece of 3d scanned data, capturing the tacit experience involved in manipulating a hot glass freeform spiral and the glass forms are also caught physically by the steel armatures.  I also think the process of hot glass working can hold the artist captive to its seductive beauty, its fluid motion, and the fact that it is a very difficult material to master.

When I was making the work the value of the elements changed in a curious way.  When first made the glass curls were removed from the kiln after a day or so annealing.  At this point there were perhaps 8 unique parts all made in a couple of hours in the hot-shop. Although hot glass is a fairly expensive and difficult process these elements did not represent a huge investment to me,  I have made this form countless times as a demonstration of freefrom manipulation.  Once laid out and examined the parts were edited down to 3, purely on aesthetic judgement and sandblasted to aid in the next phase.  I took the parts to be scanned by the Universitie’s Farro scanner,  which after the work and surfacing was done resulted in a IGES file that I could open in 3d modelling software, in my case Rhino. I then spent about a month on and off building the virtual armature to hold the glass in a frame form. Once designed and laid out flat It took 4 hours to cut the parts from mild steel on the waterjet machine.  The parts could then be assembled with the glass captured inside.

After Five weeks sitting in bubble wrap safely in my attic room the glass parts saw the light of day once more.  It was a very strange experience, like meeting an old friend; the reality of holding these physical forms was almost too familiar. I had not touched the glass parts for all the time that I had been modelling the work, but virtually, I had manipulated, rotated, and composed them for around 100 hours.

Most of the assembly was straight forward, as digital fabrication is accurate enough for my needs, however there were a few points where I had not quite been able to calculate how one part would rotate into place past the other one.  The two glass parts wrap around each other once without touching but this placement was difficult to achieve whilst also passing one part through a mounting hole.  At about 1.00am  with no second pair of hands and getting tiered, I found myself with one glass part on my shoulder, the other being slowly twisted around it and inserted into the problematic mounting hole, like some kind of  Christmas wire puzzle that you get in expensive crackers, I had to solve this problem without using too much force.

Excessive force and glass do not usually make a good combination and at this point the full realisation of the value of each part became patently clear. There was a now a huge amount of time and energy invested in each of these 2 glass parts and if one of them was to be broken there was no return, no way to reconfigure the work, as the metal had been so carefully designed to fit the glass at a certain place with a tolerance of 1mm clearance for the cushioning rubber.  With cold sweating hands I carried on,  like a bouldering problem I had to tease out the right combination of moves to finish the work, but with this problem I had no crashmat.

Glass art is often given credence or value by its finish, its polish, its glossy surface.  I used to spend 100 hours of my time grinding, fitting, joining and polishing parts of glass sculptures but Capture was a departure.  Now the Investment was virtual, the works essence lies in its digital genesis as well as its glassy fluidity and the skill invested in its making.  The age of digital fabrication is full of surprises and making this piece, for me, was my most profound.